title: Role of nitric oxide in regulation of vascular resistance in postnatal intestine.
abstract: Studies were conducted to determine whether endothelial production of nitric oxide (NO) participates in the regulation of vascular resistance in postnatal swine intestine. In vivo, intra-arterial infusion of the arginine analogue NG-monomethyl-L-arginine (L-NMMA, 10(-4) M) increased intestinal vascular resistance 34% in 3-day-old animals and 9% in 35-day-old animals (P < 0.01); similar findings were noted during infusion of 10(-3) M L-NMMA. Mechanical augmentation of gut flow rate induced intestinal vasodilation in both age groups; L-NMMA eliminated this flow-induced dilation in intestine of 3- but not 35-day-old animals. In vitro, precontracted mesenteric artery rings from both age groups relaxed to a similar extent in response to the endothelium-independent nitrovasodilator sodium nitroprusside (SNP) and the calcium ionophore A-23187; the effect of A-23187, but not SNP, was eliminated by mechanical disruption of the endothelium. Acetylcholine (ACh) and substance P (SP), agents with vascular effects that are secondary to receptor-mediated activation of NO, caused greater relaxation of rings from younger than from older animals, and this effect was attenuated by L-NMMA or methylene blue. Unstimulated accumulation of guanosine 3',5'-cyclic monophosphate (cGMP) occurred to a similar extent in vessel segments from both groups. ACh and SP increased cGMP accumulation in segments from 3- but not from 35-day-old animals. We conclude that the NO-cGMP axis participates to a greater extent in regulation of intestinal vascular resistance in 3- than in 35-day-old swine.
authors.affiliation: Department of Pediatrics, Ohio State University, Columbus 43210, USA.
authors.forename: C A
authors.initials: CA
authors.lastname: Nankervis
authors.forename: P T
authors.initials: PT
authors.lastname: Nowicki
mesh_terms: D000375:Aging / Q000502:physiology*; D000704:Analysis of Variance; D000818:Animals; D000831:Animals, Newborn; D001120:Arginine / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects; D006152:Cyclic GMP / Q000378:metabolism; D004730:Endothelium, Vascular / Q000502:physiology; D066298:In Vitro Techniques; D007261:Infusions, Intra-Arterial; D007422:Intestines / Q000098:blood supply* / Q000254:growth & development; D008638:Mesenteric Arteries / Q000187:drug effects / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000502:physiology; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D010100:Oxygen / Q000097:blood; D010313:Partial Pressure; D011189:Potassium Chloride / Q000494:pharmacology; D012039:Regional Blood Flow / Q000187:drug effects; D013552:Swine; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology*; D019323:omega-N-Methylarginine
chemical_list: D019323:omega-N-Methylarginine; D009569:Nitric Oxide; D011189:Potassium Chloride; D001120:Arginine; D006152:Cyclic GMP; D010100:Oxygen