Effect of respiratory acidosis on heart and circulation in cats, pigs, dogs and rabbits

Abstract

In closed chest cats, dogs, rabbits and pigs, anaesthetized with pentobarbital and relaxed with diallylnortoxiferinium dichloride the effects of a respiratory acidosis on heart and circulation as well as their reaction to sympathomimetic amines were studied.1. In cats and pigs a respiratory acidosis causes a rise of frequency, dp/dtmax of the left ventricle and systolic blood-pressure. In rabbits an acidosis causes no significant alteration of blood-pressure and dp/dtmax. In dogs frequency, dp/dtmax and blood-pressure decline in acidosis. In cats pretreated with reserpine a respiratory acidosis causes a negative inotropic effect and a declining of blood-pressure. After pretreating cats with phenoxybenzamine in acidosis there results a decrease of bloodpressure, but a rise of dp/dtmax and frequency; after pretreating with pindolol in acidosis dp/dtmax and frequency decline, but blood-pressure remains unaltered. The e~eetiveness o/ sympathomimetic amines on heart and circulation is di-minished in acidosis. This diminution is most significant in those animMs (cat, pig) with the most augmented sympathetic tonus in acidosis, but experiments performed with reserpinized cats indicated that the augmented sympathetic tonus can not be the only cause for the diminished efficiency of adrenergic stimulant amines in acidosis.3. Biochemical studies performed in acidosis showed a rise of K +, Mg 2+, inorganic phosphate and glucose in serum and a decrease of Mg 2+ in the heart muscle.

Evaluation of blood electrolyte alterations in cats during elec-tive laparoscopic ovariectomy

“…One study reported a change towards hyponatremia in dogs, but without significance, in response to hemodynamic instability [1]. As regard to iMg level, the findings were compatible with the study carried out by Kohler et al in which was demonstrated that mobilization of magnesium from body tissues takes place if body pH is altered [14].…”

Right ventricular performance during increased afterload impaired by hypercapnic acidosis in conscious dogs.

“…Previous investigators have measured increased circulating catecholamines during acute hypercapnic acidosis (Morris and Miller, 1962;Tenney, 1956), although Kohler et al (1972) observed unchanged plasma norepinephrine and epinephrine concentrations during acute hypercapnic acidosis in anesthetized dogs. The unchanged myocardial response to isoproterenol infusion during hypercapnic acidosis differs from past studies, which have observed diminished responsiveness to isoproterenol during acute hypercapnic acidosis (Page and Olmstead, 1951;Tenney, 1956;Atkinson and Rand, 1972).…”