URINARY 17-HYDROXYCORTICOSTEROID EXCRETION IN GUINEA-PIGS WITH HYPOTHALAMIC LESIONS

1966 ◽  
Vol 53 (3) ◽  
pp. 369-381 ◽  
Author(s):  
Bryant Benson
Keyword(s):  
Guinea Pig ◽  
Cold Exposure ◽  
Guinea Pigs ◽  
Insulin Injection ◽  
Self Control ◽  
Base Line ◽  
Acth Secretion ◽  
Anatomic Site ◽  
Hypothalamic Lesions ◽  
Bilateral Lesions

ABSTRACT An attempt was made to localize an anatomic site in the hypothalamus where mechanisms are to be found for the control of pituitary adrenocorticotrophin (ACTH) secretion in the adult male guinea-pig. Daily urinary 17-hydroxycorticosteroid (17-OHCS) excretion and the effects of cold exposure and insulin on base-line 17-OHCS excretion levels were determined preoperatively. Each animal acted as a self control. Bilateral electrolytic coagulation lesions were placed in a variety of hypothalamic sites in sixty-eight animals, and base-line 17-OHCS excretion levels and the 17-OHCS response to cold exposure and insulin injection were again determined. Preoperative and postoperative values were compared and the ablated anatomic sites noted. Animals with bilateral lesions in the ventromedian and dorsomedian nuclei displayed a significant reduction in daily 17-OHCS excretion, and 17-OHCS responses to cold exposure and insulin injection. Animals with posterior hypothalamic lesions and sham operated animals had postoperative daily 17-OHCS values and 17-OHCS responses to cold and to insulin that were above or equal to the preoperative values. It was postulated that in the guinea-pig the hypothalamic mechanisms in control of ACTH are to be found in the middle and anterior hypothalamus, in the neuropil associated with the ventromedian and dorsomedian nuclei.

Airway neutral endopeptidase-like enzyme modulates tachykinin-induced bronchoconstriction in vivo

1988 ◽  
Vol 65 (6) ◽  
pp. 2585-2591 ◽  
Author(s):  
D. J. Dusser ◽  
E. Umeno ◽  
P. D. Graf ◽  
T. Djokic ◽  
D. B. Borson ◽  
...  
Keyword(s):  
Substance P ◽  
Guinea Pig ◽  
Vagus Nerve ◽  
Nerve Stimulation ◽  
Guinea Pigs ◽  
Vagus Nerve Stimulation ◽  
Neutral Endopeptidase ◽  
Base Line ◽  
Pulmonary Resistance

To determine whether neutral endopeptidase (NEP), also called enkephalinase (EC 3.4.24.11), modulates the effects of exogenous and endogenous tachykinins in vivo, we studied the effects of aerosolized phosphoramidon, a specific NEP inhibitor, on the responses to aerosolized substance P (SP) and on the atropine-resistant response to vagus nerve stimulation (10 V, 5 ms for 20 s) in guinea pigs. SP alone (10(-7) to 10(-4) M; each concentration, 7 breaths) caused no change in total pulmonary resistance (RL, P greater than 0.5). Phosphoramidon (10(-4) M, 90 breaths) caused no change either in base-line RL (P greater than 0.5) or in the response to aerosolized acetylcholine (P greater than 0.5). However, in the presence of phosphoramidon, SP (7 breaths) produced a concentration-dependent increase in RL at concentrations greater than or equal to 10(-5) M (P less than 0.001). Phosphoramidon (10(-7) to 10(-4) M; each concentration, 90 breaths) induced a concentration-dependent potentiation of SP-induced bronchoconstriction (10(-4) M, 7 breaths; P less than 0.01). Vagus nerve stimulation (0.5-3 Hz), in the presence of atropine, induced a frequency-dependent increase in RL (P less than 0.001). Phosphoramidon potentiated the atropine-resistant responses to vagus nerve stimulation (P less than 0.001) at frequencies greater than 0.5 Hz. The tachykinin antagonist [D-Arg1,D-Pro2,D-Trp7,9,Leu11]-substance P abolished the effects of phosphoramidon on the atropine-resistant response to vagus nerve stimulation (2 Hz, P less than 0.005). NEP-like activity in tracheal homogenates of guinea pig was inhibited by phosphoramidon with a concentration producing 50% inhibition of 5.3 +/- 0.8 nM.(ABSTRACT TRUNCATED AT 250 WORDS)

Cold acclimation of guinea pig depressed contraction of cardiac papillary muscle

1999 ◽  
Vol 276 (4) ◽  
pp. R923-R928
Author(s):  
Shuichi Takagi ◽  
Yasuki Kihara ◽  
Futoshi Toyoda ◽  
Tetsuo Morita ◽  
Shigetake Sasayama ◽  
...  
Keyword(s):  
Sarcoplasmic Reticulum ◽  
Guinea Pig ◽  
Cold Acclimation ◽  
Papillary Muscle ◽  
Cold Exposure ◽  
Guinea Pigs ◽  
Sectional Area ◽  
Cross Sectional ◽  
Time To Peak ◽  
Rate Dependent

Guinea pigs were exposed to 5°C for 3 wk, and the contractions of myocardial papillary muscle were compared with preparations dissected from control animals kept at ∼25°C. Developed tension of the papillary muscle per cross-sectional area was significantly ( t-test, P < 0.05) decreased after cold exposure (19,200 ± 8,160 vs. 3,020 ± 2,890 dyne/cm2; 1 Hz). Time to peak tension was significantly faster in cold-exposed guinea pigs (126.4 ± 11.1 ms; 1 Hz) than in controls (162.7 ± 8.7 ms). The magnitude of the developed tension after application of ryanodine (2 mM) to muscles from cold-exposed animals was decreased to 37.5 ± 8.3% of control at 1 Hz, whereas in muscles from control animals, tension was decreased to 82.4 ± 7.7%. The ryanodine-sensitive component of contraction was not significantly changed in control guinea pigs at frequencies >0.5 Hz, whereas in muscles from cold-acclimated guinea pigs, there was a “positive staircase.” These results suggested that reversal of the Na+/Ca2+exchanger is predominantly involved in the positive staircase in control guinea pigs, whereas rate-dependent increases in the Ca2+ store in the sarcoplasmic reticulum may be involved in the staircase after cold acclimation.

Endogenous AA metabolites and their possible role in tracheal smooth muscle tone in guinea pigs

1990 ◽  
Vol 69 (1) ◽  
pp. 26-32 ◽  
Author(s):  
K. Yamane ◽  
T. Kobayashi
Keyword(s):  
Arachidonic Acid ◽  
Smooth Muscle ◽  
Guinea Pig ◽  
Guinea Pigs ◽  
Contractile Response ◽  
Muscle Tone ◽  
Tracheal Smooth Muscle ◽  
Base Line ◽  
Active Tension ◽  
Lipoxygenase Pathway

The effects of endogenous arachidonic acid (AA) metabolites on inherent tone and histamine-induced constriction were studied in guinea pig tracheal smooth muscle. Inhibitors of either cyclooxygenase (indomethacin) or lipoxygenase (AA 861) significantly diminished the inherent tone of the muscle. Antagonists of prostaglandins (SC 19220) or leukotrienes (FPL 55712) also diminished the inherent tone, whereas an inhibitor of thromboxane synthase (OKY 046) had no significant effect. These results show that the metabolites of the lipoxygenase pathway as well as prostaglandins also participate in the maintenance of inherent tone. To reexamine the previously reported augmentation of histamine constriction induced by the inhibitors and the antagonists, we compared the active tension of the muscle measured from the maximum relaxed level as the base line to eliminate the fluctuation of inherent tone. Such comparison revealed that the inhibitors and the antagonists have no augmentative effect on either the maximum response to histamine or the concentration required to produce 50% of maximum active tension and that there is functional synergism between the exogenously added histamine and the endogenously produced AA metabolites. Therefore the zero active tension is useful as a base line to compare the contractile response of a drug-treated preparation with that of a nontreated preparation.

Relationship between bodyweight and spleen size in guinea-pigs

1977 ◽  
Vol 11 (3) ◽  
pp. 175-180 ◽  
Author(s):  
C. Garcia-Carrillo
Keyword(s):  
Guinea Pig ◽  
Individual Variation ◽  
Guinea Pigs ◽  
Normal Weight ◽  
Spleen Weight ◽  
Base Line ◽  
Spleen Size ◽  
Coefficients Of Variation ◽  
Length And Area

The normal weight, width, length and area of the guinea-pig spleen and their corresponding relationships to bodyweight were studied. A total of 224 males and 229 females were selected at weights ranging from 150 to 1000 g. Females had significantly larger and heavier spleens than males, but exhibited greater individual variation in spleen weight, width and length. The width and/or length of the spleen presented the smallest coefficients of variation, suggesting the feasibility of using these parameters together with the calculated base line to establish whether a spleen comes from a normal guinea-pig or from an animal having an infection causing splenomegaly.

INSULIN SENSITIVITY AND ADRENOCORTICAL FUNCTION IN GUINEA-PIGS WITH HYPOTHALAMIC LESIONS

1966 ◽  
Vol 53 (4) ◽  
pp. 663-672 ◽  
Author(s):  
Bryant Benson
Keyword(s):  
Insulin Sensitivity ◽  
Guinea Pig ◽  
Guinea Pigs ◽  
Adrenocortical Function ◽  
Anatomic Site ◽  
Single Intraperitoneal Injection ◽  
Hypothalamic Nuclei ◽  
Electrolytic Lesions ◽  
Sugar Levels ◽  
Insulin Hypersensitivity

ABSTRACT Insulin hypersensitivity was displayed by adult, male guinea-pigs with bilateral, electrolytic lesions in the anterior and middle hypothalamus. The increased hypoglycaemic response to a single intraperitoneal injection of insulin (0.5 U/kg) was followed by marked hypoglycaemia unresponsiveness compared with preoperative control values. The most effective lesions were those centered in and about the ventromedian and dorsomedian hypothalamic nuclei, either ablating a portion of the anterior median eminence or leaving it entirely intact. Animals with both types of lesions had lower fasting blood sugar levels and marked adrenal regression as evidenced by reduced adrenal weights and decreased levels of 17-hydroxycorticosteroid excretion. It is postulated that lesions in the ventromedian and dorsomedian hypothalamus which interfere with adrenocortical function correspond in anatomic site to those which render the guinea-pig more sensitive to insulin.

Glycogen in guinea pig neutrophils: Ultrastructural study of neutrophils at the intradermal site of BCG injection

1983 ◽  
Vol 41 ◽  
pp. 726-727
Author(s):  
Corazon D. Bucana
Keyword(s):  
Bone Marrow ◽  
Guinea Pig ◽  
Electron Density ◽  
Peritoneal Cavity ◽  
Ultrastructural Study ◽  
Guinea Pigs ◽  
Random Distribution ◽  
Glycogen Content ◽  
Polymorphonuclear Neutrophils ◽  
Ultrastructural Studies

In the circulating blood of man and guinea pigs, glycogen occurs primarily in polymorphonuclear neutrophils and platelets. The amount of glycogen in neutrophils increases with time after the cells leave the bone marrow, and the distribution of glycogen in neutrophils changes from an apparently random distribution to large clumps when these cells move out of the circulation to the site of inflammation in the peritoneal cavity. The objective of this study was to further investigate changes in glycogen content and distribution in neutrophils. I chose an intradermal site because it allows study of neutrophils at various stages of extravasation.Initially, osmium ferrocyanide and osmium ferricyanide were used to fix glycogen in the neutrophils for ultrastructural studies. My findings confirmed previous reports that showed that glycogen is well preserved by both these fixatives and that osmium ferricyanide protects glycogen from solubilization by uranyl acetate.I found that osmium ferrocyanide similarly protected glycogen. My studies showed, however, that the electron density of mitochondria and other cytoplasmic organelles was lower in samples fixed with osmium ferrocyanide than in samples fixed with osmium ferricyanide.

Inhibition of Human and Animal Platelet Adhesiveness to Glass Bead Columns by Adenosine, Dipyridamole, Chlorpromazine and Acetylsalicylic Acid

1976 ◽  
Vol 36 (02) ◽  
pp. 401-410 ◽  
Author(s):  
Buichi Fujttani ◽  
Toshimichi Tsuboi ◽  
Kazuko Takeno ◽  
Kouichi Yoshida ◽  
Masanao Shimizu
Keyword(s):  
Guinea Pig ◽  
Acetylsalicylic Acid ◽  
Guinea Pigs ◽  
Glass Bead ◽  
Animal Species ◽  
Inhibitory Effect ◽  
Rabbit Platelet ◽  
Platelet Adhesiveness

SummaryThe differences among human, rabbit and guinea-pig platelet adhesiveness as for inhibitions by adenosine, dipyridamole, chlorpromazine and acetylsalicylic acid are described, and the influence of measurement conditions on platelet adhesiveness is also reported. Platelet adhesiveness of human and animal species decreased with an increase of heparin concentrations and an increase of flow rate of blood passing through a glass bead column. Human and rabbit platelet adhesiveness was inhibited in vitro by adenosine, dipyridamole and chlorpromazine, but not by acetylsalicylic acid. On the other hand, guinea-pig platelet adhesiveness was inhibited by the four drugs including acetylsalicylic acid. In in vivo study, adenosine, dipyridamole and chlorpromazine inhibited platelet adhesiveness in rabbits and guinea-pigs. Acetylsalicylic acid showed the inhibitory effect in guinea-pigs, but not in rabbits.

INCORPORATION OF IODIDE INTO ORGANIC COMPOUNDS IN THE GUINEA PIG THYROID

1963 ◽  
Vol 43 (1) ◽  
pp. 110-118 ◽  
Author(s):  
R. Ekholm ◽  
T. Zelander ◽  
P.-S. Agrell
Keyword(s):  
Guinea Pig ◽  
Protein Binding ◽  
Organic Compounds ◽  
Guinea Pigs ◽  
Microsomal Fraction ◽  
Thyroid Tissue ◽  
Particulate Fraction ◽  
Supernatant Fraction ◽  
Hydrolysis Of

ABSTRACT Guinea pigs, kept on a iodine-sufficient diet, were injected with Na131I and the thyroids excised from 45 seconds to 5 days later. The thyroid tissue was homogenized and separated into a combined nuclear-mitochondrial-microsomal fraction and a supernatant fraction by centrifugation at 140 000 g for one hour. Protein bound 131iodine (PB131I) and free 131iodide were determined in the fractions and the PB131I was analysed for monoiodotyrosine (MIT), diiodotyrosine (DIT) and thyroxine after hydrolysis of PB131I. As early as only 20 minutes after the Na131I-injection almost 100% of the particulate fraction 131I was protein bound. In the supernatant fraction the protein binding was somewhat less rapid and PB131I values above 90% of total supernatant 131I were not found until 3 hours after the injection. In all experiments the total amount of PB131I was higher in the supernatant than in the corresponding particulate fraction. The ratio between supernatant PB131I and pellet PB131I was lower in experiments up to 3 minutes and from 2 to 5 days than in experiments of 6 minutes to 20 hours. Hydrolysis of PB131I yielded, even in the shortest experiments, both MIT and DIT. The DIT/MIT ratio was lower in the experiments up to 2 hours than in those of 3 hours and over.

A QUANTITATIVE STUDY OF SPERMATOGENESIS IN RATS BEARING HYPOTHALAMIC LESIONS OF MAMMILLARY AND SUPRA-CHIASMATIC NUCLEI

1969 ◽  
Vol 60 (2) ◽  
pp. 276-280
Author(s):  
Bernard A. Rüedi
Keyword(s):  
Quantitative Analysis ◽  
Quantitative Study ◽  
Germinal Cell ◽  
Suprachiasmatic Nuclei ◽  
Hypothalamic Lesions ◽  
Cell Counts ◽  
Significant Change ◽  
Bilateral Lesions ◽  
Made In

ABSTRACT A quantitative analysis of spermatogenesis has been made in rats bearing bilateral lesions of the lateral mammillary nuclei or of the suprachiasmatic nuclei of the hypothalamus. There was no significant change in the germinal cell counts in lesioned rats as compared either with normal or with sham operated rats.

Method for recording ECG's in unanesthetized guinea pigs

1965 ◽  
Vol 20 (5) ◽  
pp. 1091-1093 ◽  
Author(s):  
Alfred Richtarik ◽  
Thomas A. Woolsey ◽  
Enrique Valdivia
Keyword(s):  
Guinea Pig ◽  
Guinea Pigs ◽  
Standing Posture ◽  
Factors Affecting ◽  
Rapid Succession ◽  
Unanesthetized Animals ◽  
Animal Size ◽  
Four Electrodes

A device for use in recording ECG's from guinea pigs is described. It is constructed of Plexiglas and consists of a base with four electrodes (separated by plastic ridges) on which the animal stands. The animal's activity is restricted by a removable box, the ends and top of which are adjustable to compensate for variations in animal size. The device permits recording of ECG's in rapid succession from quiet, unanesthetized animals in normal standing posture. Results obtained with the method are reported. apparatus for guinea pig ECG; time relations guinea pig ECG; normal ECG, guinea pig; factors affecting quality of ECG recordings from guinea pigs Submitted on October 21, 1964

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