Oliver Carrier

Alteration of extracellular calcium dependence in vascular tissue by reserpine

The extracellular calcium dependence of isolated rabbit aortic strips for contractile responses induced by norepinephrine(NE) and KCl after pretreatment in vivo with reserpine (0.9 mg/kg, i.m; 24 hr) has been investigated. Strips were tested in normal or calcium-free Ringers solution. In normal Ringers, contractile responses of aortae from reserpine-pretreated animals to NE or KCl were significantly potentiated. In calcium-free Ringers, reserpine pretreatment reduced extracellular calcium dependence for contractions induced by NE but increased the extracellular calcium requirement for KCl induced contractions. Higher aortic calcium levels of strips incubated in calcium-free Ringers indicated that reserpine pretreatment significantly increased the affinity of aortic tissue for calcium. After incubation for four hours in calcium-free Ringers, such strips contained 33.5% of control tissue calcium, while only 13.9% of control tissue calcium remained in the normal strips. Thus reserpine pretreatment facilitates the accumulation of a tissue calcium pool and about 21% of this calcium is more firmly bound than normal tissue calcium. These data suggest that the increase in bound calcium is related to the development of supersensitivity and decreased extracellular calcium dependence of NE-induced contractions.

Inhibition of cholesterol-induced vascular lesions by dietary reserpine

Summary Rabbits fed a diet containing 4 % cholesterol developed fatty aortic intimas and myocardiums in seven weeks. By ten weeks the fat had increased. When animals were given the same diet plus 0.2 mg/100 g reserpine the fatty deposits were smaller. Food consumption and body weight changes for the two experimental groups and for control animals did not differ greatly. In the reserpine group blood pressure was lower than controls throughout the experiment, while in the cholesterol group it was lower during the first and last thirds of the experiment. Tissue calcium content in the aortae of the reserpine group was significantly lower than in control animals. In the cholesterol group calcium was lower but not significantly so. The effect of reserpine may be due either to its hypotensive effect or to its lowering of the calcium content of the aortae.

Effect of hydrogen ion changes on vascular resistance in isolated artery segments

Isolated arterial segments, 1 cm in length and 0.5–1.0 mm in diameter, were perfused with Tyrodes solution titrated to various levels of pH. Po2, Pco2, and temperature were held at physiological levels; the perfusion pressure was held at 100 mm Hg, and flow was measured by a drop counter. There was a linear increase in flow as the pH was decreased from 7.4, 0.05 units at a time, with an increase of 87% obtained at pH 7.15. As the pH was further decreased, the flow dropped until at pH 6.8 it leveled off slightly above control level. When the pH was raised, there was an initial 35% decrease in flow by the time pH 7.50 was reached, followed by an increase, reaching 50% above control level at 7.65. At still higher pHs a precipitous decrease in conductance occurred, flow leveling off slightly below control level at pH 7.80. Consistent results were obtained on 45 vessels using Tyrodes solution titrated to the desired pH with lactic acid, hydrochloric acid, acetic acid, sulfuric acid, nitric acid, sodium hydro...

Decrease of Venous Return Caused by Right Atrial Pulsation

Over 250 records were made in 15 dogs to show the effect of artificially induced right atrial pressure pulsations on venous return. In not a single instance did the induced pulsations increase venous return, but often it decreased venous return. On the other hand, a very slight decrease in mean right atrial pressure down to the pressure level that the veins collapse completely was shown to increase venous return markedly. These experiments indicate that the benefit to venous return which results from rhythmic cardiac or respiratory suction is caused by a decrease in mean right atrial pressure.

The protective action of reserpine against diet-induced atrial thrombosis.

Abstract One hundred TS female mice were fed a high-fat, low-protein, choline-deficient diet. Fifty of these mice received an intraperitoneal injection of 0.1 mg/kg body weight of reserpine daily. In the non-reserpinized group 48 of 50 mice had died by 20 weeks. The incidence of atrial thrombosis within the nonreserpine group was 65% by 40 weeks. In the reserpine-treated group 15 of 50 mice had died by 20 weeks. The incidence of atrial thrombosis in the reserpine-treated group by 40 weeks was 34%. Reserpine reduced significantly the incidence and severity of atrial thrombosis and in addition, extended longevity. In 25 mice that received a normal diet without reserpine there were no cardiac lesions.

Protection by reserpine of carbon tetrachloride-induced hepatic necrosis☆

Abstract One hundred and twenty-five female RF strain mice were divided at random into five groups. Group I received a single injection of 0.1 ml/kg CCl4. Group II received a single injection of 0.1 mg>kg reserpine simultaneously with CCl4. Group III was pretreated for 7 days with reserpine and then received CCl4. Group IV served as a control group and group V was pretreated with reserpine for 7 days. Livers from groups IV and V were analyzed for calcium content and all groups were studied histologically. All injections were subcutaneous. Only those mice (group III) which were pretreated with reserpine were protected against CCl4 induced hepatic necrosis. Reserpine pretreatment also resulted in an elevated liver calcium content (group V). This protection against CCl4 induced hepatic necrosis could be associated with the increase in hepatic calcium since both resulted from reserpine pretreatment.