ISSN:0031-7012    

DOI:10.1159/000137231

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Li+ is reported to reduce sensitivity of α-adrenergic receptors to NE. The present investigation was designed to investigate the mechanism of this decreased sensitivity on the rat isolated seminal vesicle. In innervated preparations, 1.35 x 10–3M Li+ (i) shifted the concentration-response curves of NE, methoxamine, ACh and BaCl2 to the right and reduced their maximum responses; (ii) antagonized the leftward shift and the enhancement of maximum responses to NE by cocaine (2.9 x 10–4 M), and (iii) reduced only the maximum responses to KC1. In denervated preparations, 1.35 x 10–3M Li+ shifted the concentration response curve of NE to the left without any change in the maximum responses. The antagonistic effects of Li+ on maximal responses to NE, ACh and KC1 observed in innervated preparations were significantly increased in Ca++-free medium. Li+ (1.35 x 10–3M) increased NE uptake by the seminal vesicle significantly. It is concluded that decreased sensitivity of the seminal vesicle to NE by Li+ could be due to an increase in the uptake of NE and to a nonspecific postsynaptic spasmolyti

ISSN:0031-7012    

DOI:10.1159/000137232

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0031-7012    

DOI:10.1159/000137139

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Urotensin I (UI) was found to elicit dose-related relaxation responses in isolated helical strips of the rat tail artery. The responses were not prevented by adrenergic, cholingergic or histaminergic blocking agents. Competitive and non-competitive components of antagonism were observed to noradrenaline-, 5-hydroxytryptamine-, and arginine vasopressin-induced contractions. Atropine caused a direct relaxation of the isolated vascular tissues, as well as a significant potentiation of UI responses.

ISSN:0031-7012    

DOI:10.1159/000137233

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0031-7012    

DOI:10.1159/000137140

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

Acepromazine (500 μg), tetrodotoxin (0.5 μg) and magnesium sulphate (7.5 mg twice) given intracerebroventricularly increased the doses of ouabain given by continuous intravenous infusion, required to induce arrhythmias and death. Acepromazine (150 μg kg–1) was also effective when administered intravenously. Acepromazine (1.5 mg kg–1) and tetrodotoxin (4-6μg kg–1) given intravenously did not protect against, and even increased, the toxicity of ouabain. Both substances decreased blood pressure and increased heart rate. Tetrodotoxin, but neither acepromazine nor magnesium sulphate given intracerebroventricularly, induced a decrease in the heart rate before ouabain infusion. Acepromazine (500 μg) and tetrodotoxin (0.5 μg), but not magnesium sulphate, given intracerebroventricularly, decreased the blood pressure before ouabain infusion. The results are discussed in relation to the effects of those substances and ouabain on the circulation, and to the fact that the cardiac arrhythmias induced by high doses of ouabain and the protection obtained with tetrodotoxin and magnesium sulphate are, at least in part, mediated by the central ner

ISSN:0031-7012    

DOI:10.1159/000137234

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:0031-7012    

DOI:10.1159/000137141

出版商:S. Karger AG    

年代:1968

数据来源: Karger

摘要:

The pharmacokinetics of tritiated vinblastine in rats has indicated a considerable excretion of the alkaloid through bile into the intestinal lumen. The present study was undertaken to find out whether the presence of the alkaloid in the lumen of small intestine alters the normal transport of nutrients across the small intestine. This was done by measuring the in vitro D-glucose uptake by slices of small intestine of rats pretreated with vinblastine. Vinblastine pretreatment was done by filling the lumen of in vivo segments of small intestine of rats with different concentrations of the alkaloid for 30 and 60 min before uptake was measured. A significant dose-dependent reduction in D-glucose uptake was observed.

ISSN:0031-7012    

DOI:10.1159/000137235

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Chang liver cell cultures were exposed to the tricyclic antidepressants, chlorimipramine (CIM), nortriptyline (NT), amitriptyline (AT), imipramine (IM), and doxepin (DOX). Loss of enzymes into surrounding media and cytopathic changes were used to quantitate cytotoxicity. Time- and concentration-related cytotoxic effects were evident for all drugs. The order of cytotoxic potency was CIM > NT > AT > IM > DOX. All tricyclic antidepressants tested lowered the surface tension of the salt solution contained in the tissue culture media and the order of their surface activity was identical to that of their cytotoxicity. It is postulated that the cellular toxicity induced by tricyclic antidepressants in vitro is related to a function of their surface activity.

ISSN:0031-7012    

DOI:10.1159/000137236

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Effects of chronic parenteral carbohydrate administration on hepatic microsomal enzyme activity were studied in the rat. Intraperitoneal injections of either glucose or fructose (2.88 g daily for 7 days) significantly decreased hepatic cytochrome P-450 content and ethyl-morphine N-demethylase and aniline hydroxylase activities. By the 5th day, cytochrome P-450 content decreased to 70-76% and ethylmorphine N-demethylase activity to 66–69% of control values. Aniline hydroxylase activity was not significantly altered until the 7th day, by which time it was 77–79% of control values. In vivo assessment of hepatic drug-metabolizing capacity using antipyrine as a test drug confirmed these decreases observed in vitro. Two major conclusions of these experiments are that such variables as time and dose of carbohydrate administration can affect the magnitude of the changes produced and that each parameter measured exhibited a distinctive pattern of change with time. Chronic carbohydrate administration produced hepatic fatty infiltration and glycogen depletion. Since all groups received identical amounts of specific nutrients, fatty infiltration was probably due to increased lipogenesis with decreased hepatic oxidative metabolism of fat. During these experiments neither hypoinsulinemia nor increased levels of cyclic AMP were observed. The molecular mechanisms responsible for hepatic glycogen depletion and decreased MFO activities remain to be establis

ISSN:0031-7012    

DOI:10.1159/000137237

出版商:S. Karger AG    

年代:1979

数据来源: Karger