Lack of control of renin release by adrenergic nervous system in the aglomerular toadfish.
Aglomerular toadfish, Opsanus tau, release renin in response to hemorrhage or vasodilator drugs, presumably by stimulating a renal arterial baroreceptor. We aimed to determine whether the adrenergic nervous system and prostaglandins play a role in the control of renin release in unanesthetized toadfish kept in 50% seawater. Isoproterenol (1 microgram/kg) increased plasma renin activity (PRA) fourfold and decreased blood pressure (BP); both effects were abolished by a concomitant infusion of propranolol. Propranolol itself slightly decreased the basal level of heart rate and BP, but not that of PRA. Norepinephrine (1 microgram/kg) increased BP, but did not change PRA. Repeated injection of 6-hydroxydopamine did not alter resting levels of either PRA or BP. Monoamine-specific nerve fluorescence activity could not be demonstrated in association with arterioles of kidneys from intact toadfish or from those treated with monoamine oxidase inhibitor and norepinephrine (5 mg/kg). Furthermore, treatment of toadfish with indomethacin (10 or 20 mg/kg) prevented neither the increase in PRA nor the reduction in BP after a massive hemorrhage. These results indicate that renin release in toadfish primarily occurs in response to a reduction in renal arterial pressure, whereas it appears unlikely that the adrenergic nervous system or prostaglandins have a significant role in the control of renin release.
Nakamura
Y
Y
Department of Physiology and Biophysics, University of Tennessee, Memphis 38163.
Madey
M A
MA
Nishimura
H
H
Quach
D
D
Barajas
L
L
D000804:Angiotensin II / Q000097:blood; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002395:Catecholamines / Q000378:metabolism; D004573:Electrolytes / Q000097:blood; D005260:Female; D005399:Fishes / Q000378:metabolism*; D005880:Gills / Q000378:metabolism; D006339:Heart Rate / Q000187:drug effects; D006651:Histocytochemistry; D007213:Indomethacin / Q000494:pharmacology; D007668:Kidney / Q000378:metabolism; D007678:Kidney Glomerulus / Q000502:physiology*; D008297:Male; D016627:Oxidopamine / Q000494:pharmacology; D011863:Radioimmunoassay; D012083:Renin / Q000378:metabolism*; D013564:Sympathetic Nervous System / Q000378:metabolism*; D013566:Sympathomimetics / Q000494:pharmacology
D002395:Catecholamines; D004573:Electrolytes; D013566:Sympathomimetics; D000804:Angiotensin II; D016627:Oxidopamine; D012083:Renin; D007213:Indomethacin