Channel catfish possess a functional renin-angiotensin system that regulates blood pressure, making them a suitable model for studying ANGII in freshwater-adapted fish.
Channel catfish exhibit functional RAS regulating blood pressure; leaves open suitability as model for ANGII research in other fish.
Salination of freshwater (FW) bodies has the potential to affect homeostatic regulation of osmotic and volume balance in FW organisms. The renin-angiotensin system (RAS) plays an important role in volume balance by maintaining blood pressure in marine and seawater acclimated euryhaline fish, but little is known about the RAS in FW adapted fish. The purpose of the present study was to first determine if the FW channel catfish ( Ictalurus punctatus ), demonstrates evidence of a functional RAS. Channel catfish (n = 6) were implanted with a catheter in the dorsal aorta to measure dorsal aortic pressure (P DA ) and infuse drugs. Infusion of [Asn 1 ,Val 5 ,Asn 9 ]-angiotensin I (ANGI) at 100, 400, and 1000 ng/kg significantly increased P DA in a dose dependent manner ( P < 0.05). Pretreatment with 2 mg/kg of the angiotensin converting enzyme inhibitor, Captopril (CAP), essentially eliminated the pressor response to the highest dose of ANGI ( P < 0.05). Finally, infusion of 400 ng/kg [Asn 1 ,Val 5 ]-angiotensin II (ANGII) significantly increased P DA from baseline ( P < 0.05). The results suggest that channel catfish appear to have an operational RAS and may serve as a suitable model in which to study the role of ANGII in blood pressure regulation in FW adapted fish.
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Hunt et al. (2018) studied this question.
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