Pressor response to a postural change in cirrhosis: an experimental study in the CCI4-treated rat

1992 ◽  
Vol 82 (2) ◽  
pp. 147-156 ◽  
Author(s):  
Arieh Bomzon ◽  
Avraham Weinbroum ◽  
Laurence M. Blendis
Keyword(s):  
Pressor Response ◽  
Contributory Factor ◽  
Postural Change ◽  
Systemic Hypotension ◽  
Arterial Blood ◽  
The Face ◽  
Cirrhotic Patients

1. Systemic hypotension, blunted cardiovascular responsiveness to noradrenaline and an abnormal hypertensive pressor response to a postural change have been described in cirrhotic patients. 2. We have examined the role of blunted responsiveness in these abnormalities by studying basal arterial blood pressure and its response to a postural change (vertical head-up 90° tilting) in conscious and pithed CCl4-treated (cirrhotic) rats, as well as assessing the pressor response to noradrenaline in vivo and the vascular contractile response to noradrenaline in vitro. 3. A diminished hypotensive response to a change in posture was found in pre-cirrhotic portal hypertensive rats, whereas an inverted hypertensive pressor response in the face of systemic hypotension occurred in the cirrhotic rats with portal hypertension. 4. The inverted pressor response was abolished in the pithed portal hypertensive cirrhotic rats. 5. The pressor response to noradrenaline in vivo in conscious cirrhotic rats and the vascular contractile responsiveness to noradrenaline in vitro were intact. 6. We conclude that blunted responsiveness to noradrenaline is not a contributory factor to the development of systemic hypotension or the inverted pressor response to a change in posture in cirrhosis.

scholarly journals Angiotensin II infusion in vivo does not modulate cortisol secretion in the late-gestation ovine fetus

1998 ◽  
Vol 275 (2) ◽  
pp. R357-R362 ◽  
Author(s):  
Kirsten R. Poore ◽  
I. Ross Young ◽  
Benedict J. Canny ◽  
Geoffrey D. Thorburn
Keyword(s):  
Angiotensin Ii ◽  
Adrenal Gland ◽  
Late Gestation ◽  
Treatment Groups ◽  
Arterial Blood ◽  
Basal Cortisol ◽  
Ovine Fetus

Maturation of the fetal adrenal gland is critical for the onset of ovine parturition. It has long been proposed that the fetal adrenal gland may be under inhibitory influences during late gestation. In vitro evidence has suggested that angiotensin II may be such an inhibitory factor and may help to prevent a premature increase in cortisol concentrations. The aim of this study was to test the effect of angiotensin II infusion in vivo on basal cortisol concentrations and fetal adrenal responsiveness to an ACTH-(1—24) challenge. Fetuses received a continuous infusion of either angiotensin II (100 ng ⋅ min−1 ⋅ kg−1; n = 7) or saline (2 ml/h; n = 4), which commenced at 140 days of gestation (GA) and continued for a total of 50 h. Adrenal responsiveness to the administration of ACTH-(1—24) (5 μg/kg) was determined during angiotensin II or saline infusions at both 2 and 48 h after infusion onset. Angiotensin II had no significant effect on adrenal responsiveness after acute (2 h) or chronic (48 h) infusion. There was no effect of saline or angiotensin II infusion on basal immunoreactive ACTH or cortisol concentrations after 2 h, but there was a significant increase in basal cortisol concentrations in both treatment groups by 48 h, probably reflecting the normal rise in cortisol concentrations at this GA. Mean arterial blood pressure was significantly increased in angiotensin II-infused fetuses only. This study has therefore found no evidence to suggest that angiotensin II infusion in vivo modulates fetal basal cortisol concentrations or adrenal responsiveness in the last week of gestation, in contrast with previous in vitro studies. These results throw into question the proposed role of angiotensin II as a negative modulator of adrenal function in the ovine fetus.

In vitro and in vivo inhibition of renin by fatty acids.

1978 ◽  
Vol 234 (6) ◽  
pp. E593 ◽  
Author(s):  
T A Kotchen ◽  
W J Welch ◽  
R T Talwalkar
Keyword(s):  
Blood Pressure ◽  
Fatty Acids ◽  
Linoleic Acid ◽  
Angiotensin Ii ◽  
Neutral Lipids ◽  
Pressor Response ◽  
Arterial Blood ◽  
Arachidonic Acids

Circulating neutral lipids inhibit the in vitro renin reaction. To identify the inhibitor(s), free fatty acids were added to human renin and homologous substrate. Capric, lauric, palmitoleic, linoleic, and arachidonic acids each inhibited the rate of angiotensin I production in vitro (P less than 0.01). Inhibition by polysaturated fatty acids (linoleic and arachidonic) was less (P less than 0.01) after catalytic hydrogenation of the double bonds. To evaluate an in vivo effect of renin inhibition intra-arterial blood pressure responses to infusions of renin and angiotensin II (5.0 microgram) were measured in anephric rats (n = 6) before and after infusion of linoleic acid (10 mg iv). Mean increase of blood pressure to angiotensin II before (75 mmHg +/- 9) and after (90 +/- 12) linoleic acid did not differ (P greater than 0.05). However, the pressor response to renin after linoleic acid (18 +/- 3) was less (P less than 0.00)) than that before (102 +/- 13). In summary, several fatty acids inhibit the in vitro renin reaction, and in part inhibition is dependent on unsaturation. Linoleic acid also inhibits the in vivo pressor response to renin. These results suggest that fatty acids may modify the measurement of plasma renin activity and may also affect angiotensin production in vivo.

Role of platelet-activating factor-acether in mediating guinea pig anaphylaxis

Science ◽  
1986 ◽  
Vol 232 (4746) ◽  
pp. 58-60 ◽  
Author(s):  
H Darius ◽  
DJ Lefer ◽  
JB Smith ◽  
AM Lefer
Keyword(s):  
Guinea Pig ◽  
Platelet Activating Factor ◽  
Respiratory Arrest ◽  
Independent Component ◽  
Systemic Hypotension ◽  
Isolated Lung

The pathophysiology of anaphylaxis is very complex, and the sequelae of events are not fully explained in terms of the effects of histamine and peptide leukotrienes alone. Platelet-activating factor (1-O-alkyl-2-acetyl-sn-glyceryl-3-phosphorylcholine, PAF-acether) has been detected in animals undergoing anaphylaxis. Injection of synthetic PAF-acether induces similar effects, including bronchoconstriction, respiratory arrest, systemic hypotension, neutropenia, and thrombocytopenia. The results reported here demonstrate that the histamine- and leukotriene-independent component of guinea pig anaphylaxis in vivo and in isolated lung parenchymal strips in vitro is mediated by PAF-acether. However, PAF-acether is not responsible for the anaphylaxis-induced thrombocytopenia.

The Role of Polyphenols in the Modulation of Plasma Non-Enzymatic Antioxidant Capacity (NEAC)

2012 ◽  
Vol 82 (3) ◽  
pp. 228-232 ◽  
Author(s):  
Mauro Serafini ◽  
Giuseppa Morabito
Keyword(s):  
Antioxidant Capacity ◽  
Dietary Intervention ◽  
Ex Vivo ◽  
The Body ◽  
Dietary Polyphenols ◽  
Enzymatic Antioxidant ◽  
Endogenous Antioxidant

Dietary polyphenols have been shown to scavenge free radicals, modulating cellular redox transcription factors in different in vitro and ex vivo models. Dietary intervention studies have shown that consumption of plant foods modulates plasma Non-Enzymatic Antioxidant Capacity (NEAC), a biomarker of the endogenous antioxidant network, in human subjects. However, the identification of the molecules responsible for this effect are yet to be obtained and evidences of an antioxidant in vivo action of polyphenols are conflicting. There is a clear discrepancy between polyphenols (PP) concentration in body fluids and the extent of increase of plasma NEAC. The low degree of absorption and the extensive metabolism of PP within the body have raised questions about their contribution to the endogenous antioxidant network. This work will discuss the role of polyphenols from galenic preparation, food extracts, and selected dietary sources as modulators of plasma NEAC in humans.

Anti-obesity role of Aster glehni extract: in vivo and in vitro effects

Planta Medica ◽  
2012 ◽  
Vol 78 (11) ◽  
Author(s):  
HM Lee ◽  
TG Ahn ◽  
CW Kim ◽  
HJ An
Keyword(s):  
In Vitro Effects

A Molecular Approach to Immunoscintigraphy: A Study of the T-Antigen Conformation on the Surface of Tumors

1987 ◽  
Vol 26 (01) ◽  
pp. 1-6 ◽  
Author(s):  
S. Selvaraj ◽  
M. R. Suresh ◽  
G. McLean ◽  
D. Willans ◽  
C. Turner ◽  
...  
Keyword(s):  
Monoclonal Antibodies ◽  
Tumor Cell ◽  
T Antigen ◽  
Human Carcinomas ◽  
Animal Tumor ◽  
Synthetic Antigens

The role of glycoconjugates in tumor cell differentiation has been well documented. We have examined the expression of the two anomers of the Thomsen-Friedenreich antigen on the surface of human, canine and murine tumor cell membranes both in vitro and in vivo. This has been accomplished through the synthesis of the disaccharide terminal residues in both a and ß configuration. Both entities were used to generate murine monoclonal antibodies which recognized the carbohydrate determinants. The determination of fine specificities of these antibodies was effected by means of cellular uptake, immunohistopathology and immunoscintigraphy. Examination of pathological specimens of human and canine tumor tissue indicated that the expressed antigen was in the β configuration. More than 89% of all human carcinomas tested expressed the antigen in the above anomeric form. The combination of synthetic antigens and monoclonal antibodies raised specifically against them provide us with invaluable tools for the study of tumor marker expression in humans and their respective animal tumor models.

THYROID STIMULATORS AND THYROID STIMULATION

1971 ◽  
Vol 66 (3) ◽  
pp. 558-576 ◽  
Author(s):  
Gerald Burke
Keyword(s):  
Regulatory System ◽  
Control Site ◽  
Thyroid Cell ◽  
Primary Control ◽  
Physico Chemical ◽  
Site Of Action ◽  
Long Acting

ABSTRACT A long-acting thyroid stimulator (LATS), distinct from pituitary thyrotrophin (TSH), is found in the serum of some patients with Graves' disease. Despite the marked physico-chemical and immunologic differences between the two stimulators, both in vivo and in vitro studies indicate that LATS and TSH act on the same thyroidal site(s) and that such stimulation does not require penetration of the thyroid cell. Although resorption of colloid and secretion of thyroid hormone are early responses to both TSH and LATS, available evidence reveals no basic metabolic pathway which must be activated by these hormones in order for iodination reactions to occur. Cyclic 3′, 5′-AMP appears to mediate TSH and LATS effects on iodination reactions but the role of this compound in activating thyroidal intermediary metabolism is less clear. Based on the evidence reviewed herein, it is suggested that the primary site of action of thyroid stimulators is at the cell membrane and that beyond the(se) primary control site(s), there exists a multifaceted regulatory system for thyroid hormonogenesis and cell growth.

THE ROLE OF POLYETHYLENIMINE IN ENHANCING PERFORMANCE OF GLUTAMATE BIOSENSORS

2018 ◽  
Vol 8 (3) ◽  
pp. 36-41
Author(s):  
Diep Do Thi Hong ◽  
Duong Le Phuoc ◽  
Hoai Nguyen Thi ◽  
Serra Pier Andrea ◽  
Rocchitta Gaia
Keyword(s):  
First Generation ◽  
Good Reproducibility ◽  
Complex Matrices ◽  
Long Term Stability ◽  
In Vitro Characterization ◽  
Glutamate Oxidase

Background: The first biosensor was constructed more than fifty years ago. It was composed of the biorecognition element and transducer. The first-generation enzyme biosensors play important role in monitoring neurotransmitter and determine small quantities of substances in complex matrices of the samples Glutamate is important biochemicals involved in energetic metabolism and neurotransmission. Therefore, biosensors requires the development a new approach exhibiting high sensibility, good reproducibility and longterm stability. The first-generation enzyme biosensors play important role in monitoring neurotransmitter and determine small quantities of substances in complex matrices of the samples. The aims of this work: To find out which concentration of polyethylenimine (PEI) exhibiting the most high sensibility, good reproducibility and long-term stability. Methods: We designed and developed glutamate biosensor using different concentration of PEI ranging from 0% to 5% at Day 1 and Day 8. Results: After Glutamate biosensors in-vitro characterization, several PEI concentrations, ranging from 0.5% to 1% seem to be the best in terms of VMAX, the KM; while PEI content ranging from 0.5% to 1% resulted stable, PEI 1% displayed an excellent stability. Conclusions: In the result, PEI 1% perfomed high sensibility, good stability and blocking interference. Furthermore, we expect to develop and characterize an implantable biosensor capable of detecting glutamate, glucose in vivo. Key words: Glutamate biosensors, PEi (Polyethylenimine) enhances glutamate oxidase, glutamate oxidase biosensors

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