Hemodynamic effects of pyruvate infusion in dogs

Purpose: Although pyruvate supplementation enhances endurance in humans and increases cardiac output in dogs, its effects on cardiac and peripheral vascular function are not known. Thus, we assessed the cardiovascular effects of pyruvate infusion. Materials and Methods: Aortic, left ventricular (LV), and pulmonary (Ppa) pressures and LV stroke volume (Sv_lv; derived from aortic flow probe) were measured after thoracotomy in eight anesthetized dogs. LV area or volume changes were measured using either an epicardial echocardiography (n = 6) or a conductance catheter (n = 2). LV end-systolic elastance (Ees_lv) and preload recruitable stroke force (PRSF_lv) relations, as estimates of contractility, were generated by transient inferior vena cave occlusion. Simultaneous stroke volume to arterial pressure relations during the occlusions were used to measure arterial elastance (Ea), and steady-state systemic and pulmonary vascular resistances were used as measures of arterial tone. Graded doses of pyruvate (8, 16, and 32 mg/kg/min), dobutamine (positive control) and propranolol (negative control) and placebo (volume control) were sequentially given. Results: Dobutamine increased Ees_lv PRSF_lv, whereas propranolol had the opposite effect on Ees_lv and PRSF_lv. Pyruvate at 32 mg/kg/min increased heart rate, Ppa, and SV_lv and decreased LV end-diastolic area, and systemic vascular resistance without changing arterial pressure, Ees_lv PRSF_lv. or Ea. Conclusions: We conclude that pyruvate infusion in normal dogs induces venodilation but does not alter either cardiac contractility or arterial tone.