Effect of strontium on the contractile properties of postnatally developing rat heart ventricles

1985 ◽  
Vol 63 (1) ◽  
pp. 9-17 ◽  
Author(s):  
Matti Vornanen
Keyword(s):  
Rat Heart ◽  
Age Groups ◽  
Contractile Properties ◽  
Neonatal Rat ◽  
Calcium Stores ◽  
Adult Rats ◽  
Adult Rat ◽  
Twitch Potentiation ◽  
Developing Rat ◽  
T System

The effects of substitution of calcium (Ca) by an equimolar concentration of strontium (Sr) on isometric contractions of isolated ventricular muscle from postnatally developing rat heart were studied. The duration of contraction and the time-to-peak tension were increased in all age groups although much less in the adult rats than in the neonates. The contractile force was increased in the muscles of rats between 1 and 14 days of age but was depressed in the older animals. The prominent rest-twitch potentiation of neonatal rat heart in Ca− Tyrode was totally eliminated by Sr, whereas a clear rest-twitch potentiation was induced by this cation in the adult rat heart, in which tissue the potentiation is normally absent in Ca− Tyrode. The maximal twitch potentiation by rest in Ca− Tyrode and the positive inotropic effect of Sr substitution grew from birth up to day 9 and from then gradually declined towards the level of adult rat heart by the end of the 3rd postnatal week. The phase of increasing rest-twitch potentiation coincides fairly well with the known development of sarcoplasmic reticulum and the phase of decline with the appearance of the T system of the sarcolemma. It is suggested that the qualitative changes in the contractile properties of developing rat heart during the 3rd postnatal week are due to the more efficient utilization of intracellular calcium stores, owing to the development of the T system.

scholarly journals Localization and partial characterization of ADP-ribosylation products in hearts from adult and neonatal rats

1990 ◽  
Vol 270 (3) ◽  
pp. 591-597 ◽  
Author(s):  
K J Piron ◽  
K K McMahon
Keyword(s):  
Rat Heart ◽  
Cardiac Development ◽  
Neonatal Rat ◽  
Nuclear Fraction ◽  
Adult Rats ◽  
Adp Ribosylation ◽  
Adult Rat ◽  
Snake Venom Phosphodiesterase ◽  
Rat Hearts ◽  
Neonatal Rat Heart

The subcellular distributions of endogenous ADP-ribosylation products in hearts from 1-day-old neonatal and adult rats were investigated. In adult rat heart a 52 kDa mono-ADP-ribosylation product was identified in the plasma membrane fraction. In contrast, in neonatal rat heart a 130 kDa poly-ADP-ribosylation product was present in the nuclear fraction. The monomeric and polymeric nature of the two ADP-ribosylation products was determined by their sensitivity to thymidine and by analysis of their snake venom phosphodiesterase products. NADP+ enhanced both the mono- and polymeric reactions. The ADP-ribose-protein linkage of the adult 52 kDa product was stable to 1 h of treatment with hydroxylamine (0.5 M) and mercury ions, but was sensitive to alkali and a 12 h treatment with hydroxylamine (1 M). This is suggestive of an arginine linkage. The 130 kDa poly-ADP-ribosylation product from the neonatal rat heart was alkalilabile but stable to both hydroxylamine and HgCl2. This implies the presence of an unusual linkage in the 130 kDa product. The presence of these different ADP-ribosylation products in adult and neonatal rat hearts suggests the possible importance of these proteins and their ADP-ribosylation during cardiac development.

Contractile function of isolated young and adult rat heart cells

1987 ◽  
Vol 253 (6) ◽  
pp. H1484-H1491 ◽  
Author(s):  
R. A. Haworth ◽  
P. Griffin ◽  
B. Saleh ◽  
A. B. Goknur ◽  
H. A. Berkoff
Keyword(s):  
Rat Heart ◽  
Contractile Function ◽  
Heart Cells ◽  
Isolated Cells ◽  
Adult Rats ◽  
Adult Rat ◽  
Contraction Duration ◽  
Velocity Of Shortening ◽  
Myofilament Activation ◽  
Rat Heart Cells

The stimulated contractile function of aerobic isolated adult rat heart cells was assessed by laser light diffraction. Cells were maintained for up to 8 h by attachment to a cover slip and continuous perfusion in a chamber on the microscope stage. On stimulation such cells beat as though unattached. Cells showed a negative staircase which was reduced by increasing Ca or isoproterenol. Ryanodine caused a positive staircase on stimulation, which was enhanced by increasing Ca or isoproterenol or by using cells from younger rats. For beats of constant contraction duration, there was a linear relationship between the magnitude of cell shortening and the velocity of shortening, independent of the concentration of extracellular Ca. We conclude the following. 1) The beat characteristics of isolated cells are very similar to those of papillary muscle. 2) Attachment of cells need not alter their unloaded shortening characteristics. 3) Cells appear to contract against an internal load, to an extent determined by the degree of myofilament activation. 4) Cells from young rats require less extracellular Ca than those from adult rats for the same beat magnitude.

Characterization of Mitotic Neurons Derived From Adult Rat Hypothalamus and Brain Stem

2002 ◽  
Vol 87 (2) ◽  
pp. 1076-1085 ◽  
Author(s):  
Jenafer Evans ◽  
Colin Sumners ◽  
Jennifer Moore ◽  
Matthew J. Huentelman ◽  
Jie Deng ◽  
...  
Keyword(s):  
Tissue Culture ◽  
Membrane Potential ◽  
Brain Stem ◽  
Adult Brain ◽  
Neonatal Rat ◽  
Peak Current Density ◽  
Adult Rats ◽  
Peak Current ◽  
Rat Hypothalamus ◽  
Adult Rat

Embryonic or neonatal rat neurons retain plasticity and are readily grown in tissue culture, but neurons of the adult brain were thought to be terminally differentiated and therefore difficult to culture. Recent studies, however, suggest that it may be possible to culture differentiated neurons from the hippocampus of adult rats. We modified these procedures to grow differentiated neurons from adult rat hypothalamus and brain stem. At day 7 in tissue culture and beyond, the predominant cell types in hypothalamic and brain stem cultures had a stellate morphology and could be subdivided into two distinct groups, one of which stained with antibodies to the immature neuron marker α-internexin, while the other stained with the astrocyte marker GFAP. The α-internexin positive cells were mitotic and grew to form a characteristic two-dimensional cellular network. These α-internexin positive cells coimmunostained for the neuronal markers MAP2, type III β-tubulin, and tau, and also bound tetanus toxin, but were negative for the oligodendrocyte marker GalC and also for the neurofilament triplet proteins NF-L, NF-M, and NF-H, markers of more mature neurons. Patch-clamp analysis of these α-internexin positive cells revealed small Ca2+ currents with a peak current of −0.5 ± 0.1 pA/pF at a membrane potential of −20 mV ( n = 5) and half-maximal activation at −30 mV ( n = 5). Na+ currents with a peak current density of −154.5 ± 49.8 pA/pF at a membrane potential of −15 mV ( n = 5) were also present. We also show that these cells can be frozen and regrown in tissue culture and that they can be efficiently infected by viral vectors. These cells therefore have the immunological and electrophysiological properties of immature mitotic neurons and should be useful in a variety of future studies of neuronal differentiation and function.

Calcium exchange, structure, and function in cultured adult myocardial cells

1987 ◽  
Vol 252 (2) ◽  
pp. H314-H324 ◽  
Author(s):  
G. A. Langer ◽  
J. S. Frank ◽  
T. L. Rich ◽  
F. B. Orner
Keyword(s):  
Rat Heart ◽  
Neonatal Rat ◽  
Adult Rat ◽  
Ec Coupling ◽  
Exchange Structure ◽  
Ethanesulfonic Acid ◽  
And Function ◽  
Cellular Ca ◽  
Adult Cells

Cells digested from adult rat heart and cultured for 14 days demonstrate all the structural elements, in mature form, associated with the process of excitation-contraction (EC) coupling. The transverase tubular (TT) system is well developed with an extensive junctional sarcoplasmic reticulum (JSR). In nonphosphate-containing buffer contraction of the cells is lost as rapidly as zero extracellular Ca concentration ([Ca]o) solution is applied (less than 10 s) and a negative contraction staircase is produced on increase of stimulation frequency. Structurally and functionally the cells have the characteristics of adult cells in situ. 45Ca exchange and total 45Ca measurement in N-2-hydroxyethylpiperazine N'-2-ethanesulfonic acid (HEPES)-buffered perfusate define three components of cellular Ca: a rapidly exchangeable component (t1/2 less than 25 s) accounting for 36% of total Ca, a slowly exchangeable component (t1/2 53 min) accounting for 7% of total Ca, and the remaining 57% cellular Ca is “inexchangeable” (demonstrates no significant exchange within 60 min). The slowly exchangeable component can be increased 10-fold within 60 min by addition of phosphate to the perfusate. The Ca distribution and exchange characteristics are little different from those of 3-day cultures of neonatal rat heart previously studied [Langer, G. A., J. S. Frank, and L. M. Nudd. Am. J. Physiol. 237 (Heart Circ. Physiol. 6): H239-H246, 1979]. The results suggest that the cells are representative of adult cells in situ and that both sarcolemmal-bound and sarcoplasmic reticular Ca contribute to the component of Ca that is rapidly exchangeable.

scholarly journals Intercellular Communication within the Rat Anterior Pituitary Gland. XV. Properties of Spontaneous and LHRH-Induced Ca2+ Transients in the Transitional Zone of the Rat Anterior Pituitary in Situ

Endocrinology ◽  
2013 ◽  
Vol 154 (1) ◽  
pp. 400-409 ◽  
Author(s):  
Kazuki Hattori ◽  
Nobuyuki Shirasawa ◽  
Hikaru Suzuki ◽  
Takanobu Otsuka ◽  
Ikuo Wada ◽  
...  
Keyword(s):  
Anterior Pituitary ◽  
Cyclopiazonic Acid ◽  
Transitional Zone ◽  
Neonatal Rat ◽  
Neonatal Rats ◽  
Adult Rats ◽  
Adult Rat ◽  
Voltage Dependent

In the transitional zone of the rat anterior pituitary, spontaneous and LHRH-induced Ca2+ dynamics were visualized using fluo-4 fluorescence Ca2+ imaging. A majority of cells exhibited spontaneous Ca2+ transients, while small populations of cells remained quiescent. Approximately 70% of spontaneously active cells generated fast, oscillatory Ca2+ transients that were inhibited by cyclopiazonic acid (10 μm) but not nicardipine (1 μm), suggesting that Ca2+ handling by endoplasmic reticulum, but not Ca2+ influx through voltage-dependent L-type Ca2+ channels, plays a fundamental role in their generation. In the adult rat anterior pituitary, LHRH (100 μg/ml) caused a transient increase in the Ca2+ level in a majority of preparations taken from the morning group rats killed between 0930 h and 1030 h. However, the second application of LHRH invariably failed to elevate Ca2+ levels, suggesting that the long-lasting refractoriness to LHRH stimulation was developed upon the first challenge of LHRH. In contrast, LHRH had no effect in most preparations taken from the afternoon group rats euthanized between 1200 h and 1400 h. In the neonatal rat anterior pituitary, LHRH caused a suppression of spontaneous Ca2+ transients. Strikingly, the second application of LHRH was capable of reproducing the suppression of Ca2+ signals, indicating that the refractoriness to LHRH had not been established in neonatal rats. These results suggest that responsiveness to LHRH has a long-term refractoriness in adult rats, and that the physiological LHRH surge may be clocked in the morning. Moreover, LHRH-induced excitation and associated refractoriness appear to be incomplete in neonatal rats and may be acquired during development.

scholarly journals Interrelationship of glutathione–cystine transhydrogenase and glutathione reductase in developing rat intestine

1973 ◽  
Vol 132 (3) ◽  
pp. 623-631 ◽  
Author(s):  
Beatrice States ◽  
Stanton Segal
Keyword(s):  
Glutathione Reductase ◽  
Reductase Activity ◽  
Rat Intestine ◽  
Adult Rats ◽  
Adult Rat ◽  
Mucosal Layer ◽  
Old Rats ◽  
Developing Rat ◽  
Gssg Reductase

1. Glutathione reductase and glutathione–cystine transhydrogenase activity in supernatant fractions of whole homogenates and homogenates of mucosal and muscular layers were determined in developing rat intestine after determination of the optimum conditions for assay of the two enzymes. In jejunum from adult rat, the Km values for GSSG reductase and GSH–cystine transhydrogenase activities were 0.25mm-GSSG and 0.23mm-cystine respectively. 2. The two activities could be differentiated by stability studies since GSSG reductase was stable at 60°C for 10min and could be stored at 4°C for 24h without loss of activity. GSH–cystine transhydrogenase, on the other hand, was denatured at 60°C and completely inactive after 24h storage at 4°C. 3. Based on calculations of total activities, both enzymes increased from the eighteenth day until the animals were young adults. 4. Total GSSG reductase activity increased at a greater rate with age than total GSH–cystine transhydrogenase activity as evidenced by activity ratios for GSH–cystine transhydrogenase/GSSG reductase of 0.44 and 0.12 in ileum from suckling and adult rats respectively, and 0.31 and 0.24 in jejunum from suckling and adult rats respectively. 5. In mucosa from adult rats GSSG reductase was more active in the ileum than in the jejunum, whereas GSH–cystine transhydrogenase activity was higher in the jejunum. 6. GSH–cystine transhydrogenase was active only in the muscle cells of the ileum of 7-day-old rats but became localized primarily in the mucosal layer in the adult rat. However, GSSG reductase activity was distributed evenly between the two layers throughout the intestine.

CARTILAGE RESPONSE TO PLASMA AND PLASMA SOMATOMEDIN ACTIVITY IN RATS RELATED TO GROWTH BEFORE AND AFTER BIRTH

1981 ◽  
Vol 90 (1) ◽  
pp. 133-142 ◽  
Author(s):  
D. J. HILL ◽  
S. J. ANDREWS ◽  
R. D. G. MILNER
Keyword(s):  
Body Weight ◽  
Costal Cartilage ◽  
Basal Medium ◽  
Tail Length ◽  
Rat Plasma ◽  
Neonatal Rat ◽  
Postnatal Life ◽  
Fetal Life ◽  
Adult Rats ◽  
Adult Rat

Cartilage response to plasma, plasma somatomedin activity, body weight and length were measured in rats from 15 days of fetal age to 37 days postnatally. The metabolic activity of costal cartilage was assessed by the incorporation of [35S]sulphate in basal medium and after stimulation by plasma. It was found that (a) A significant stimulation of isotope uptake above basal levels occurred in the presence of 15% standard adult rat plasma at every age studied. (b) The degree of stimulation, a measure of cartilage sensitivity to plasma growth factors, increased through the latter part of fetal life but fell after birth. A high degree of cartilage stimulation was seen on day 6 of postnatal life. (c) The changes in cartilage sensitivity and in the stimulated isotope uptake, resembled the changes observed in growth rate for body weight, nose–rump length and tail length. (d) Plasma somatomedin activity measured by the pig costal cartilage assay was low in the fetus and neonate but rose to adult values 9 days after birth. However, plasma from fetal or neonatal rats tested on cartilage from rats of the same age was equipotent to adult rat plasma. (e) Plasma from hypophysectomized adult rats had a low potency in stimulating isotope uptake by neonatal rat cartilage but was equipotent to normal adult rat plasma in its action on fetal cartilage. (f) The action of plasma from hypophysectomized rats on fetal cartilage was unaffected by dialysis but was destroyed by incubation with trypsin.

scholarly journals Preproenkephalin mRNA expression in developing rat heart and in cultured ventricular cardiac muscle cells

1989 ◽  
Vol 258 (1) ◽  
pp. 73-78 ◽  
Author(s):  
J P Springhorn ◽  
W C Claycomb
Keyword(s):  
Cardiac Muscle ◽  
Cell Cultures ◽  
Translational Regulation ◽  
Muscle Cells ◽  
Heart Cell ◽  
Developmentally Regulated ◽  
Adult Rats ◽  
Cardiac Muscle Cells ◽  
Adult Rat ◽  
Developing Rat

Heart muscle tissue has previously been reported to have the highest content of preproenkephalin (ppEnk) mRNA of any tissue in the adult rat. We have determined that it is present in the ventricular cardiac muscle cells of the heart and is developmentally regulated. The expression of ppEnk mRNA was observed to be low throughout the first 2 weeks of postnatal development and decreases substantially during week 3. Expression was again low by week 4, but by adulthood (approx. 3 months), it reached a maximum. ppEnk mRNA was actively expressed in primary cardiac muscle cell cultures prepared from both neonatal and adult rats. Its steady-state content in cell cultures was observed to be increased by cyclic AMP and 3-isobutyl-1-methylxanthine. The phorbol ester phorbol 12-myristate 13-acetate elicited a transient effect (i.e. an increase was observed at 4 h and a return to control values by 24 h). We speculate that enkephalin may play a multi-functional role in the differentiation of neonatal cardiac muscle cells and in the terminally differentiated adult heart cell. We demonstrate that the primary culture systems employed in this study will be useful models with which to explore both transcriptional and translational regulation of ppEnk mRNA in the heart.

Comparison of extraction methods for insulin-like growth factor-binding proteins prior to measurement of insulin-like growth factor-I in undernourished neonatal and adult rat serum

1994 ◽  
Vol 140 (2) ◽  
pp. 257-263 ◽  
Author(s):  
F Rivero ◽  
L Goya ◽  
A M Pascual-Leone
Keyword(s):  
Growth Factor ◽  
Binding Proteins ◽  
Extraction Methods ◽  
Rate Of Change ◽  
Neonatal Rat ◽  
Insulin Like Growth Factor ◽  
Adult Rats ◽  
Rat Serum ◽  
Adult Rat ◽  
Igf I

Abstract Insulin-like growth factors (IGFs) are considered to be endocrine regulators during development, and different species have been used for the study of these factors during the perinatal period. The neonatal rat is a very useful model widely utilized to study endocrine alterations throughout the developmental period; few references in the literature present the neonatal rat as a model for the study of IGFs however. This study was undertaken to compare two extraction methods, acid–ethanol cryoprecipitation (AEC) and formic acid–acetone (FA), for the removal of IGF-binding proteins (IGFBPs) from neonatal and adult rat serum in fed (control) and undernourished populations prior to measurement of IGF-I by radioimmunoassay (RIA). The IGF-I values obtained by RIA following AEC or FA extraction were compared with those obtained following gel filtration (GF), which is considered to be the reference method. Western ligand blotting was used to determine IGFBPs in unextracted serum and after AEC or FA extraction of serum from rats of 10 and 20 days of age and adult rats in both populations. Although serum IGF-I levels after AEC or FA in adult control rats were comparable with those obtained following GF, a significant correlation was found only after AEC extraction both in fed and undernourished adult rats. During the neonatal period, at 10 and 20 days, serum IGF-I levels after AEC or FA extraction were very different from those obtained after GF, especially in undernourished populations, and the correlation was very poor at 10 and 20 days of age in both populations studied. The IGFBP radioligand blots showed a different rate of change in control and undernourished rats during the period studied. Changes in IGFBP-3 and the band at 30 kDa are reported in both control and undernourished animals. The different proportions of the three major IGFBPs remaining after AEC or FA extraction were also shown. We conclude that AEC extraction, originally validated for use in human serum, is also satisfactory for use in adult but not in neonatal rat serum. However, FA extraction was not a useful method for the rat serum. In neonatal rat serum, the only reliable extraction method was GF. Journal of Endocrinology (1994) 140, 257–263

Developmental pattern of TRH-degrading activity and TRH content in rat pancreas

1984 ◽  
Vol 106 (1) ◽  
pp. 102-108 ◽  
Author(s):  
Sonia Aratan-Spire ◽  
Bryan Wolf ◽  
Paul Czernichow
Keyword(s):  
Adult Life ◽  
Postnatal Period ◽  
Neonatal Rat ◽  
Adult Rats ◽  
Thyrotrophin Releasing Hormone ◽  
Developmental Patterns ◽  
Rat Pancreas ◽  
Adult Rat ◽  
Gastro Intestinal Tract ◽  
Peak Value

Abstract. Thyrotrophin-releasing hormone (TRH), like several other neuropeptides, has been detected in the gastro-intestinal tract of adult rats. More recently, elevated concentrations of TRH have been found in the neonatal rat pancreas. This study was undertaken to evaluate pancreatic TRH degrading activity (TRH-DA) in infant rats from birth until adult life. Pancreatic TRH of age-matched rats was also measured by radioimmunoassay. TRH-DA was present in normal adult rat pancreas; though absent at birth and in the early postnatal period up to day 7, this activity was detected during the remainder of the developmental period. TRH content (pg ± sem per pancreas) was 1139 ± 88 on day 1, reached a peak value of 7360 ± 758 at day 2 and then decreased steadily to adult level. TRH-DA has been found to be present at birth in hypothalamus and liver but not in plasma. The developmental patterns of TRH-DA in plasma and in pancreas were parallel and seem to be thyroid hormone dependent. The absence of TRH-DA in the neonatal pancreas may also be related to the high TRH concentrations detected in this organ during the neonatal period.

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