title: Effects of vasoactive intestinal peptide on myocardial performance.
abstract: It is now recognized that stimulation of the vagus releases both acetylcholine (ACh) and vasoactive intestinal peptide (VIP). Whereas ACh depresses cardiac function, recent data indicate that VIP may have a cardiostimulatory effect. Exogenously administered VIP appears to enhance left ventricular (LV) contractile function; however, whether endogenously released VIP alters LV performance is not known. Accordingly, we evaluated the effects of exogenous VIP and endogenously released VIP during vagal stimulation after muscarinic and beta-adrenergic blockade (VS-B) on LV performance using pressure-volume analysis. Eight anesthetized open-chest dogs instrumented to measure LV pressure and volume (conductance catheter) were pretreated with atropine (0.1 mg/kg) and propranolol (1 mg/kg). The cervical vagi were transected. Hemodynamic data were obtained at steady state and during transient vena caval occlusion. Exogenous intravenous VIP (0.05 microgram/kg-1 x min-1) increased HR minimally [2.1 +/- 0.9% increase; P = not significant (NS)] but significantly increased maximum first time derivative of left ventricular pressure (dP/dtmax; 29.4 +/- 19.9% increase; P < 0.05) and the slope of the end-systolic pressure-volume relation (Ees; 3.1 +/- 1.3 to 8.9 +/- 4.2 mmHg/ml; P < 0.05). Minimum first time derivative of left ventricular pressure (dP/dtmin) decreased 22 +/- 16.2% (P < 0.05), and the time constant of isovolumic relaxation (tau) decreased 38 +/- 18% (P < 0.05). During VS-B (20 Hz, 15 v, 5 min), HR increased significantly (98 +/- 11 to 130 +/- 26 beats/min; P < 0.05). Ees also increased significantly (3.3 +/- 1.6 vs. 5.2 +/- 2.8 mmHg/ml; P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Internal Medicine, Bowman Gray School of Medicine, Wake Forest University, Winston-Salem, North Carolina 27157.
authors.forename: N P
authors.initials: NP
authors.lastname: Xenopoulos
authors.forename: R J
authors.initials: RJ
authors.lastname: Applegate
mesh_terms: D000109:Acetylcholine / Q000494:pharmacology; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D003971:Diastole / Q000187:drug effects; D004285:Dogs; D006321:Heart / Q000187:drug effects / Q000502:physiology*; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D007262:Infusions, Intravenous; D011433:Propranolol / Q000494:pharmacology; D013599:Systole / Q000187:drug effects; D014630:Vagus Nerve / Q000502:physiology; D014660:Vasoactive Intestinal Peptide / Q000008:administration & dosage / Q000031:analogs & derivatives / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D014684:Venae Cavae / Q000502:physiology
chemical_list: C048507:vasoactive intestinal peptide, 4-chloro-Phe(6)-Leu(17)-; D014660:Vasoactive Intestinal Peptide; D001285:Atropine; D011433:Propranolol; D000109:Acetylcholine