Distension of pulmonary vein-left atrial junction: Heart rate responses in conscious and anesthetized dogs

Abstract

The cardiac chronotropic effects of distension of pulmonary vein-left atrial junction were investigated in conscious dogs and in dogs anesthetized with i.v. .alpha.-chloralose (100 mg/kg) or pentobarbital (30 mg/kg). All experiments were made on trained, chonically instrumented, closed chest animals held in horizontal position. Inflation of a single small balloon in the junction elicited a tachycardic response in conscious and chloralose-anesthetized dogs; in pentobarbital anesthesia no change in heart rate was found. No transient bradycardia was found, nor any correlation between predistension heart rate and the increase in heart rate due to the distension. Anesthetic can be chosen after its modifying effect on the parameter studied is known. Only the use of trained, chronically instrumented and conscious dogs will reveal this effect.