摘要:

The role of sodium and potassium ions, and the possible involvement of the membrane sodium pump has been studied in the development of a contractile response to, and the development of tachyphylaxis to, angiotensin II. It is suggested that a membrane depolarization may have a role in the mechanism of the contractile response to angiotensin II, as responses of the rabbit aorta to angiotensin II were selectively inhibited in K-free medium. Acute or chronic increases in medium sodium, however, did not influence the response of the rabbit aorta to angiotensin II. On the rat aorta increased medium sodium concentrations potentiated the response to angiotensin II and inhibited the development of tachyphylaxis. Membrane depolarization or hyperpolarization does not appear to be part of the mechanism of development of tachyphylaxis to angiotensin II on the rat aorta, as response to both NE and angiotensin II were inhibited equally by exposure of the rat aorta to K-free medium, i.e., nonspecific desensitization occurred, as opposed to the specific desensitization which defines tachyphylaxis.

ISSN:1018-1172    

DOI:10.1159/000158204

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

The effects of L-ascorbic acid on 35S-incorporation into thoracic aorta glycosaminoglycans and upon aorta cholesterol levels were determined in hypercholesterolemic rabbits. No significant difference was observed in serum free or esterified cholesterol levels between animals receiving L-ascorbic acid supplementation or saline while maintained on a cholesterol diet (0.5%). A 15-fold higher serum cholesterol was observed in animals on the cholesterol diet to those animals which received a normal rabbit (Purina) diet. L-Ascorbic acid increased sulfated glycosaminoglycans concentrations in hypercholesterolemic rabbits which paralleled lower tissue free and esterified cholesterol levels. The 35S-specific activity of glycosaminoglycans in hypercholesterolemic animals receiving saline was much greater than in those animals receiving L-ascorbic acid. This suggests that L -ascorbic acid plays a role in the maintenance of adequate levels of aortic sulfated glycosaminoglycans. This then is a suggested biochemical mechanism of L-ascorbic acids interaction in the atherogenic process.

ISSN:1018-1172    

DOI:10.1159/000158205

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

Cultured vascular smooth muscle cells were prepared from adult rat aortas. The cells were dispersed by collagenase/elastase, and allowed to reaggregate into small spheres (50–200 µm in diameter) by plating on to cellophane. These primary cultures were incubated for 5–14 days, and then impaled with microelectrodes. The mean resting potential was –55 mV, and the mean input resistance was 9.0 MΩ. The cells were quiescent, electrically and mechanically, and electrical stimulation usually did not elicit responses. However, addition of Ba++ (1 mM) or tetraethylammonium ion (TEA; 5–15 mM) induced excitability (with accompanying contractions), either as spontaneous action potentials or by allowing responses to electrical stimulation. The cells became partially depolarized (e.g., to –36 mV) by these agents, and the input resistance increased. The frequency of spontaneous firing of the Ba++-induced spikes was affected by polarizing current pulses, as expected for pacemaker behavior. Elevation of Ca++ in the bathing solution increased the amplitude (overshoot) of the action potentials, and the spikes were blocked by verapamil (10–5M). Electron microscopy showed that the reaggregates consisted of a tight packing of elongated small-diameter cells, some of which exhibited thick and thin myofilaments and ‘dense bodies’; many cells possessed surface caveolae. The results of this study demonstrate that reaggregates of arterial smooth muscle in primary culture can maintain functional and morphological characteristics of intact arterial smooth muscle, and therefore provide a useful preparation for the study of vascular smooth muscle fun

ISSN:1018-1172    

DOI:10.1159/000158206

出版商:S. Karger AG    

年代:1979

数据来源: Karger

摘要:

A single intravenous injection of homocystine led to an increase in the number of circulating endothelial cells in the blood of rats. We observed also increased permeability of the lung capillaries, platelet sequestration and activation of the venostatic thrombosis. Endothelial injury is probably the key mechanism of thrombotic and atherosclerotic complications in homocystinuria, an inborn error of the amino acid metabolism.

ISSN:1018-1172    

DOI:10.1159/000158207

出版商:S. Karger AG    

年代:1979

数据来源: Karger

ISSN:1018-1172    

DOI:10.1159/000158208

出版商:S. Karger AG    

年代:1979

数据来源: Karger