Role of EDRF in splanchnic blood flow of normal and chronic portal hypertensive rats.
The role of endogenous endothelium-derived relaxing factor (EDRF) in splanchnic blood flow was assessed in normal and portal vein-stenosed rats (PSRs). Specific and maximal inhibition of EDRF was achieved by intravenous administration of NG-nitro-L-arginine (L-NOARG) as a 1.75 mumol/kg bolus, followed by constant infusion of 1.75 mumol/kg for 20 min. Pretreatment with L-arginine (175 mumol/kg iv) completely blocked both hypertension and the reduction in blood flow induced by L-NOARG. Pretreatment with D-arginine (175 mumol/kg iv) and prazosin (500 micrograms/kg iv) did not attenuate the pressor effect of L-NOARG. These results indicate that L-NOARG selectively blocks EDRF. The blood flow to the stomach, duodenum, jejunum, ileum, cecum, and colon in control rats was 81.1 +/- 8.7, 199.1 +/- 21.9, 153.3 +/- 20.0, 68.6 +/- 10.6, 79.4 +/- 11.8, and 59.3 +/- 7.8 ml.min-1.100 g-1, respectively, and in PSRs was 141.4 +/- 10.8, 244.0 +/- 10.4, 208.3 +/- 9.8, 126.8 +/- 13.0, 166.9 +/- 16.5, and 94.8 +/- 4.7 ml.min-1.100 g-1, respectively. Blood flow was measured using the radioactive microsphere method. L-NOARG significantly reduced blood flow to the stomach, duodenum, jejunum, ileum, cecum, and colon in control rats by 47, 44, 48, 55, 40, and 41%, respectively, and in PSRs by 30, 27, 36, 33, 28, and 23%, respectively. The magnitude of blood flow reduction in PSRs was lower than in normal rats. These results indicate that EDRF plays an important role in control of the splanchnic circulation, but its effect on the hyperdynamic circulation observed in PSRs is insignificant.
Iwata
F
F
First Department of Internal Medicine, Nagoya City University Medical School, Japan.
Joh
T
T
Kawai
T
T
Itoh
M
M
D000818:Animals; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D002908:Chronic Disease; D006975:Hypertension, Portal / Q000503:physiopathology*; D008297:Male; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D019335:Nitroarginine; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values; D012039:Regional Blood Flow / Q000187:drug effects; D012079:Renal Circulation / Q000187:drug effects; D013152:Splanchnic Circulation / Q000187:drug effects; D013737:Testis / Q000098:blood supply
D019335:Nitroarginine; D009569:Nitric Oxide; D001120:Arginine