Effects of Ketamine on Canine Cardiovascular Function

Abstract

Left ventricular contractility was assessed before and during the peak effect of ketamine in eight canine right heart bypass preparations. Myocardial contractility was defined in terms of maximum left ventricular dp/dt, the ejection fraction, and left ventricular end-diastolic and left atrial pressures at constant heart rate and cardiac inflow. Ketamine produced significant decreases in contractility and there were some indications of a dose-response pattern. The action of ketamine was dependent partly on changes in arterial pressure, as the drug caused a mild but sustained vasodilatation which was not dose-dependent. These data offer further evidence of a small and transient negative inotropic effect of ketamine.

Effects of ketamine on renal nerve activity, arterial pressure and heart rate in rats.

“…Heart rate (HR) shows a monophasic decrease. The initial decreases in both AP and HR can be ascribed to the negative inotropic and chronotropic effects of ketamine (DIAZ et al, 1976;DOWDY and KAYA, 1968;GOLDBERG et al, 1970;SHWARTZ and HORWITZ, 1975;TRABER et al, 1968) and also the effect of ketamine to relax vascular smooth muscle (YAMANAKA and DOWDY, 1974). In addition to these direct effects of ketamine on the heart and vascular smooth muscles, initial reductions in the sympathetic nerve activities, as indicated by RNA changes, probably take part in decreases in AP and HR.…”

“…These conflicting results have been explained by multiple actions of ketamine on the cardiovascular system and its neural regulatory systems. The depressor effect has been ascribed to the direct action of ketamine on the heart (DIAz et al, 1976;DOWDY and KAYA, 1968;GoLDBERG et al, 1970;SCHWARTZ and HORWITZ, 1975;TRABER et a!., 1968) and blood vessels (YAMANAKA and DOWDY, 1974). The pressor effect has been attributed to the stimulative effects of ketamine on the sympathetic nervous system: the pressor response was abolished by epidural anesthesia (TRABER and WILsON,1969) or prior treatment with hexamethonium (TRABER et al, 1970), and the carotid sinus nerve activity reduced following ketamine administration (DOWDY and KAYA, 1968).…”

Influence of Ketamine on Catecholamine Secretion in the Perfused Rat Adrenal Medulla

“…In the present work, the in vitro concentrations of ketamine for inhibiting the effect of various secretagogues used in the rat perfused adrenal medulla are not much different from those attained in vivo in laboratory animals and humans (Dowdy & Kaya, 1968: Traber et al, 1968Goldberg et al, 1970: Yamanaka & Dowdy, 1974Schwartz & Horwitz et al, 1975;McGrath et al, l975;Diaz et al 1976;Kolka et al, 1983;Sumikawa et al, 1983;Purifoy & Holz, 1984;Takara et al, 1986).…”

“…In contrast, it has been known that ketamine produces depressor effect (McGrath et al, l975;Diaz et al, 1976). The depressor effect has been ascribed to the direct action of ketamine on the heart (Dowdy & Kaya, 1968;Traber et al, 1968;Goldberg et al, 1970;Schwartz & Horwitz et al, 1975;Diaz et al 1976) and blood vessels (Yamanaka & Dowdy, 1974).…”

“…The depressor effect has been ascribed to the direct action of ketamine on the heart (Dowdy & Kaya, 1968;Traber et al, 1968;Goldberg et al, 1970;Schwartz & Horwitz et al, 1975;Diaz et al 1976) and blood vessels (Yamanaka & Dowdy, 1974). Several reports showed that ketamine inhibited the CA secretion caused by acetylcholine receptor agonists from the isolated dog adrenals perfused with modified Locke's solution (Sumikawa et al, 1983), by nicotinic agonist at concentrations which did not alter secretion induced by elevated K ＋ depolarization from cultured bovine adrenal chromaffin cells (Purifoy & Holz, 1984), and by acute cold exposure anesthesia in adult rhesus monkeys (Kolka et al, 1983).…”