Angiotensin-I- and -III-mediated cardiovascular responses in the freshwater North American eel, Anguilla rostrata: effect of Phe8 deletion.
Cardiovascular responses to synthetic eel [Asn1, Val5, Gly9]-ANG-I, ANG-III (2-8), and ANG-I (1-7) were measured in conscious and resting freshwater North American eels. Indwelling Doppler flow probes were placed on the ventral and dorsal aortas, a pressure catheter in the lienomesenteric artery, and a peptide delivery catheter in the caudal vein. Twenty-five and 150 ng.kg-1 ANG-III increased baseline cardiac output (CO) (15.23 +/- 0.31 ml.min-1.kg-1; n = 5) by 23 and 47%, respectively, by increasing stroke volume (SV) but not heart rate (HR). ANG-I (150 ng.kg-1) also elevated CO (62%) by increasing both SV (44%) and HR (14%). Estimated branchial shunting (BS) was increased by 150 ng.kg-1 ANG-I and -III suggesting that more blood perfused the arteriovenous pathway in the gills. Dorsal aortic blood pressure (PDA) (3.08 +/- 0.12 kPa) was elevated by 150 ng.kg-1 ANG-I (67%) and -III (52%). Pressor responses temporally preceded the blood flow increases and there was a significant increase in systemic vascular resistance (RSYS) at the peak pressor responses. At the peak flow responses, increased CO was solely responsible for the increase in PDA; RSYS had returned to baseline values. Pressor responses to ANG-III decayed more rapidly (18.6 min) compared with those of ANG-I and -II (36 min). ANG-I (1-7) had no measurable effect on cardiovascular function indicating that the carboxyl-terminal 8-phenylalanine is an absolute requirement for the hormonal activity of angiotensin in fishes.
Butler
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DG
Department of Zoology, University of Toronto, Ontario, Canada.
Oudit
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D000803:Angiotensin I / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D000805:Angiotensin III / Q000031:analogs & derivatives / Q000737:chemistry / Q000494:pharmacology*; D000811:Anguilla / Q000502:physiology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D005260:Female; D005880:Gills / Q000098:blood supply / Q000187:drug effects; D006339:Heart Rate / Q000187:drug effects; D006439:Hemodynamics / Q000187:drug effects*; D009132:Muscles / Q000187:drug effects; D010649:Phenylalanine / Q000494:pharmacology*; D012039:Regional Blood Flow / Q000187:drug effects; D013318:Stroke Volume / Q000187:drug effects; D018608:Ultrasonography, Doppler; D014655:Vascular Resistance / Q000187:drug effects
D000805:Angiotensin III; D010649:Phenylalanine; D000803:Angiotensin I