RELEASE OF VASOACTIVE-INTESTINAL-PEPTIDE AND NEUROPEPTIDE-Y FROM CANINE HEART

The effects of right cervical vagal and left sympathetic stimulation o n release of immunoreactive vasoactive intestinal peptide (VIP) and ne uropeptide Y (NPY) into cardiac venous and lymphatic effluent was test ed in 11 anesthetized adult mongrel dogs. After stimulation of the rig ht cervical vagus (1 ms, 20 Hz, 5 V) for 3 min, VIP output in lymphati c effluent was significantly increased at 1.90 +/- 0.56 pg/min compare d with control of 0.90 +/- 0.42 pg/min. NPY output in lymphatic efflue nt and VIP and NPY release into coronary venous effluent, as measured by the arterial-coronary sinus concentration difference, were not chan ged. After stimulation of the ansae of the left sympathetic ganglion ( 1 ms, 10 Hz, 5 V) for 3 min, NPY output in lymphatic effluent was sign ificantly increased at 4.72 +/- 1.58 pg/min compared with a control of 0.73 +/- 0.66 pg/min. VIP output in lymphatic effluent was not change d. VIP arterial-coronary sinus concentration difference decreased slig htly but significantly, and NPY arterial-coronary sinus concentration difference decreased markedly after left sympathetic stimulation. In t hree additional dogs in which coronary sinus blood flow was measured, NPY overflow during left sympathetic stimulation increased from 28.2 /- 23.5 to 129.6 +/- 212.7 pg/min. Thus VIP and NPY release from the c anine heart can be evoked by right cervical vagal and left sympathetic stimulation, respectively. VIP and NPY may play a role as cardiac non cholinergic-nonadrenergic neurotransmitters.