The effect of distension of the urinary bladder on coronary blood flow in anesthetized dogs

To determine whether distension of the urinary bladder reflexly affects coronary blood flow, experiments were performed in eleven dogs anaesthetized with sodium pentobarbitone. Both ureters were cannulated and the urinary bladder was distended with warm Ringer solution at a steady intravesical pressure. Arterial blood pressure was prevented from changing by a pressurized reservoir of warm Ringer solution connected to the femoral arteries. Coronary blood flow was measured with an electromagnetic flowmeter positioned around the origin of the left circumflex coronary artery. When the reflex increase in heart rate was prevented by atrial pacing in seven dogs, distension of the urinary bladder always caused a decrease in mean coronary blood flow. Similar results were obtained in all eleven dogs after administration of propranolol. The decrease in mean coronary blood flow was significantly reduced by atropine or bilateral cervical vagotomy, and was abolished by bretylium tosylate. The results showed that distension of the urinary bladder reflexly decreased mean coronary blood flow, a response involving efferent cardiac vagal and sympathetic pathways.