Contribution of vascular nitric oxide to basal blood pressure in conscious spontaneously hypertensive rats and normotensive Wistar Kyoto rats.
1. The aim of this study was to clarify the extent to which vascular nitric oxide contributes to basal blood pressure in conscious spontaneously hypertensive rats and normotensive Wistar Kyoto rats. 2. The contribution of vascular nitric oxide to maintenance of blood pressure was estimated by measuring the pressor response to an intravenous injection of nitric oxide synthase inhibitor, N omega-L-arginine methyl ester, given after serial injections of captopril, vasopressin V1-receptor antagonist (V1-antagonist) and ganglion blocker (pentolinium) in conscious spontaneously hypertensive and Wistar Kyoto rats aged 20-28 weeks. To estimate the 'amplifier property' of hypertrophied vasculature in spontaneously hypertensive rats, which is known to modulate pressor responses, the lower blood pressure plateau after serial injections of captopril, V1-antagonist and pentolinium and the maximum blood pressure elicited by subsequent injection of increasing doses of phenylephrine were also measured. 3. The serial injections of captopril, V1-antagonist and pentolinium decreased mean arterial pressure from 164 +/- 9 mmHg to 67 +/- 2 mmHg and from 117 +/- 2 mmHg to 49 +/- 1 mmHg in spontaneously hypertensive and Wistar Kyoto rats respectively. The subsequent injection of N omega-L-arginine methyl ester restored mean arterial pressure almost to its control levels in both spontaneously hypertensive and Wistar Kyoto rats.(ABSTRACT TRUNCATED AT 250 WORDS)
Minami
N
N
Second Department of Internal Medicine, Tohoku University School of Medicine, Sendai, Japan.
Imai
Y
Y
Hashimoto
J
J
Abe
K
K
D000818:Animals; D000959:Antihypertensive Agents / Q000494:pharmacology; D001120:Arginine / Q000031:analogs & derivatives / Q000494:pharmacology; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology*; D002216:Captopril / Q000494:pharmacology; D004730:Endothelium, Vascular / Q000378:metabolism*; D006339:Heart Rate / Q000187:drug effects; D006973:Hypertension / Q000503:physiopathology*; D008297:Male; D019331:NG-Nitroarginine Methyl Ester; D009569:Nitric Oxide / Q000037:antagonists & inhibitors / Q000502:physiology*; D010425:Pentolinium Tartrate / Q000494:pharmacology; D010880:Piperidines / Q000494:pharmacology; D015363:Quinolones / Q000494:pharmacology; D051381:Rats; D011918:Rats, Inbred SHR; D011921:Rats, Inbred WKY
D000959:Antihypertensive Agents; D010880:Piperidines; D015363:Quinolones; C068644:OPC 21268; D009569:Nitric Oxide; D001120:Arginine; D010425:Pentolinium Tartrate; D002216:Captopril; D019331:NG-Nitroarginine Methyl Ester