Abstract
In order to more precisely characterize left ventricular function in puppies, Starling ventricular function (SF)curves were compared in 12 4-8 weeks old animals. The puppies were anesthetized with morphine and chloralose, and administered practolol (PRAC) [6] or propranolol (PROP) [6]. Three SF curves were obtained: a)control, b)after beta blockade, c)after administration of 7 × blocking dose. In 3 subjects, left ventricular end diastolic pressure (EDP) was varied without controlling heart rate (HR) or afterload (AL); in 4, HR and AL were regulated; and in 5 HR, alone was controlled. AL was regulated with an intraaortic balloon to maintain mean aortic pressure within 2-5mmHg range at matched points of EDP in each curve, but pressure was allowed to increase at successive points in any given curve.
Control of HR after beta blockade did not qualitatively alter the shape of the SF curves. Regulation of AL did not affect the SF curves during the control period, but a descending limb at 8-15mmHg EDP, previously noted during 7 × blocking doses of propranolol with no AL control, was not observed. The SF curves are consistent with an increase in contractility for large doses of PRAC compared to blocking doses, and a decrease in contractility for large doses of PROP. The contractility parameter, (dp/dt)/P appeared to be preload dependent, decreasing with increasing EDP.
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Truccone, N., Spotnitz, H. & Gersony, W. INFLUENCE OF HEART RATE, AFTERLOAD AND BETA BLOCKING AGENTS ON STARLING VENTRICULAR FUNCTION CURVES IN PUPPIES. Pediatr Res 8, 355 (1974). https://doi.org/10.1203/00006450-197404000-00089
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DOI: https://doi.org/10.1203/00006450-197404000-00089