Vasopressor and depressor effects of native angiotensins and inhibition of these effects in the Japanese quail.
The amino acid sequence of angiotensin I (ANG I) from the Japanese quail, Coturnix coturnix japonica, obtained from incubation of homologous plasma and kidney extract was determined as H-Asp-Arg-Val-Tyr-Val-His-Pro-Phe-Ser-Leu-OH. A bolus, intravenous injection of native ANG I or of ANG II induced an immediate vasodepressor response and a subsequent vasopressor response in quail which has been lightly anesthetized with urethane (0.75 g/kg). The values for ED50 for the vasopressor and depressor effects of ANG II were 85 and 113 pmol/100 g body weight, respectively. The extent of the hypotension was dependent on the arterial pressure prior to injection. The effects of ANG I and II on heart rate were variable. Human [Asp1, Ile5, His9] ANG I and II were almost as potent as their quail counterparts with respect to the cardiovascular effects, but eel [Asn1, Val5, Gly9]ANG I and II were less than half as potent. Human ANG III had little effect on arterial pressure in the quail. A bolus injection (100 micrograms/100 g) or infusion (1 micrograms/100 g/min) of [Sar1, Ile8] ANG II almost abolished the cardiovascular effects of ANG I and II, but [Sar1, Ala8] ANG II and [Sar1, Thr8] ANG II, which are effective inhibitors in mammals, had no inhibitory effects. The vasopressor and depressor effects of ANG I were abolished, while those of ANG II were slightly enhanced, after injection (100 micrograms/100 g) or infusion (1 micrograms/100 g/min) of SQ14225, whereas des-Pro2 bradykinin and bradykinin potentiator B, which are effective inhibitors of ANG I converting enzyme in mammals, failed to inhibit the effect of ANG I. These results indicate that vascular ANG II receptors and ANG I converting enzyme in the quail may be different from those in mammals.
Department of Physiology, Kitasato University School of Medicine, Kanagawa, Japan.
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Takei
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Hasegawa
D015059:1-Sarcosine-8-Isoleucine Angiotensin II / Q000494:pharmacology; D000595:Amino Acid Sequence; D000803:Angiotensin I / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000804:Angiotensin II / Q000037:antagonists & inhibitors / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002216:Captopril / Q000494:pharmacology; D002320:Cardiovascular Physiological Phenomena; D002319:Cardiovascular System / Q000187:drug effects; D003370:Coturnix / Q000502:physiology*; D004524:Eels; D006339:Heart Rate / Q000187:drug effects; D006801:Humans; D007700:Kinetics; D008297:Male; D008969:Molecular Sequence Data; D011784:Quail / Q000502:physiology*; D013045:Species Specificity
D000804:Angiotensin II; D000803:Angiotensin I; D015059:1-Sarcosine-8-Isoleucine Angiotensin II; D002216:Captopril