RESUMO
Plasma renin concentrations in rats increase after bilateral adrenalectomy without sodium substitution. The effects of i.v. infused (asp1-beta-amid, val5)-angiotensin II (1 mug/kg min), felypressin (phen2, lys8-vasopressin) (40 mU/kg min) and phenylephrine (30 mug/kg min) were investigated on the increase in plasma renin concentration. These effects of the agents were compared with their actions on blood pressure, heart rate and renal hemodynamics. In rats with destroyed macula densa cells the effect of bilateral adrenalectomy without sodium substitution was also studied. Adrenalectomy still increased the plasma renin concentration. Angiotensin II and felypressin, also depressed under these conditions the elevation of plasma renin concentration caused by adrenalectomy. The mechanism of the adrenalectomy-induced renin release and its suppression by vasoconstrictor agents is discussed.
Assuntos
Adrenalectomia , Renina/sangue , Vasoconstritores/farmacologia , Angiotensina II/farmacologia , Animais , Pressão Sanguínea/efeitos dos fármacos , Felipressina/farmacologia , Inulina/metabolismo , Sistema Justaglomerular/fisiologia , Masculino , Fenilefrina/farmacologia , Ratos , Ácido p-Aminoipúrico/metabolismoRESUMO
The effect of i.v. infused (asp1-beta-amid, val5)-angiotensin II (1.0 mug/kg min), octapressin (phe2, lys8-vasopressin) (10.0 mU/kg min) and of the alpha-sympathomimetic amine phenylephrine (40.0 mug/kg min) on the stimulation of renin secretion by furosemide (10.0 mg/kg i.v.) was investigated. The vasoconstrictors abolished the renin release induced by forosemide. Studies on the clearance of p-aminohippuric acid (PAH) (i.e. renal plasma flow) showed that the action of the vasoconstrictors cannot be explained by a decrease in access of furosemide to its intrarenal sites of action. The mechanism of the suppressive action of the vasoconstrictors on renin release is discussed.
Assuntos
Furosemida/antagonistas & inibidores , Renina/metabolismo , Vasoconstritores/farmacologia , Ácidos Aminoipúricos/urina , Angiotensina II/farmacologia , Animais , Felipressina/farmacologia , Furosemida/farmacologia , Rim/irrigação sanguínea , Masculino , Fenilefrina/farmacologia , Ratos , Fluxo Sanguíneo Regional/efeitos dos fármacos , Renina/sangueRESUMO
The vasoconstrictors angiotensin II, vasopressin and the alpha-sympathomimetic phenylephrine significantly inhibit the renin release caused by the beta-sympathomimetic isoprenaline. The mechanism of the inhibition is discussed.
