The effects of nitric oxide synthase blockers on mesenteric blood flow with bile duct ligation.
OBJECTIVE
The aim of this study was to investigate the effects of nitric oxide synthesis inhibition by L-NNA (N-nitro-L-arginine) on mesenteric blood flow in bile duct ligated rats.


METHODS
Forty female Wistar rats were allocated into four groups. Only common bile duct (CBD) was dissected with midline laparotomy (sham operated), CBD is ligated for obstructive jaundice (OJ group), with CBD dissection, 20 mg/kg L-NNA was given i.p. during 14 days (sham + L-NNA group), after CBD ligation, 20 mg/kg L-NNA was given i.p. during 14 days (OJ + L-NNA group). At the end of the 14th day, the rats were re-anaesthesized, phenylephrine was administered within the left jugular vein and, arterial blood pressure monitorization was done via left carotid artery. Blood flow of the mesenteric artery (SMA) was also recorded. Resistance of the SMA was calculated and in addition, pressure responses to phenylephrine were detected. Histopathological examination of the liver and blood analyses were done.


RESULTS
The mean blood pressure levels of the rats with OJ were lower than the control group (P>0.05). Blood flow of the SMA and vascular resistance of the rats with OJ have no significant difference with other groups. In CBD ligated animals, mean blood pressure and mesenteric vascular resistance increased by L-NNA but there was no difference in mesenteric blood flow rate and vasoconstrictive response to phenylephrine. On microscopic examination of the liver with OJ, bile duct proliferation and minimal mononuclear reaction were observed which was not affected by L-NNA administration.


CONCLUSIONS
Hypotension, low systemic vascular resistance, and a reduced sensitivity to vasoconstrictors are features of cirrhosis. In obstructive jaundice impaired vascular responsiveness to vasoconstrictor stimuli like as cirrhosis was not observed and also there was no improvement by L-NNA on histopathologic findings and liver function tests.
Yuksel
Bulent C
BC
First Department of Surgery, Ankara Numune Training and Research Hospital, Ankara, Turkey.
Tanriverdi
Pinar
P
Ozel
Hakan
H
Avsar
Fatih M
FM
Topaloglu
Serdar
S
Iskit
Alper B
AB
D000818:Animals; D001652:Bile Ducts / Q000601:surgery*; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005260:Female; D006439:Hemodynamics / Q000187:drug effects / Q000502:physiology; D041781:Jaundice, Obstructive / Q000209:etiology / Q000503:physiopathology; D008026:Ligation; D008106:Liver Cirrhosis, Experimental / Q000209:etiology / Q000503:physiopathology*; D017538:Mesenteric Artery, Superior / Q000187:drug effects / Q000502:physiology*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors*; D019335:Nitroarginine / Q000494:pharmacology; D010656:Phenylephrine / Q000494:pharmacology; D011897:Random Allocation; D051381:Rats; D017208:Rats, Wistar; D012039:Regional Blood Flow / Q000187:drug effects / Q000502:physiology; D014655:Vascular Resistance / Q000187:drug effects / Q000502:physiology; D014661:Vasoconstriction / Q000187:drug effects; D014662:Vasoconstrictor Agents / Q000494:pharmacology
D004791:Enzyme Inhibitors; D014662:Vasoconstrictor Agents; D010656:Phenylephrine; D019335:Nitroarginine; D019001:Nitric Oxide Synthase