THE CARDIAC ACTION OF POSTERIOR PITUITARY EXTRACT IN PHYSIOLOGICAL DOSES, IN THE NORMAL DOG, AND AFTER PARTIAL AND COMPLETE DENERVATION OF THE HEART

Publisher Website
Google Scholar
Abstract
In the normal dog continuous infusion of dilute posterior pituitary extract produces a maximal inhibition of the heart, i.e. slowing to about one-half of the resting rate, with usually a rise in blood pressure of 10 to 30 mm. of mercury.After bilateral thoracic sympathectomy, posterior pituitary extract also produces maximal inhibition. This inhibition, like that produced in the normal dog, is abolished by atropine.After bilateral vagotomy posterior pituitary extract produces a moderate but not maximal inhibition. This inhibition is not abolished by atropine.After bilateral thoracic sympathectomy and unilateral vagotomy, posterior pituitary extract produces a maximal effect.After total denervation of the heart, posterior pituitary extract produces no inhibition of the heart and the rate is unchanged.Characteristic changes are produced by posterior pituitary extract in the electrocardiogram of normal dogs. After total denervation no change takes place.It is concluded that the slowing of the dog's heart that is produced by continuous intravenous infusion of posterior pituitary extract is entirely due to its action through the inhibitory fibres of the vagus and sympathetic nerves.

This publication has 3 references indexed in Scilit: