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Nifedipine inhibits the hypoxia-induced decrease in plasma renin activity in conscious dogs

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Hohne C., Arntz E., Krebs M. O., Boemke W., Kaczmarczyk G.

Journal of Physiology and Pharmacology

2003

tom 54

nr 2

Acute hypoxia induces a decrease in plasma renin activity (PRA), mediated, e.g., by an increase in adenosine concentration, calcium channel activity, or inhibition of ATP-sensitive potassium channels. The decrease in PRA results in a decrease in angiotensin II (AngII) and plasma aldosterone concentration (PAC). This study investigates whether these hypoxia-induced mechanisms can be inhibited by the L-type voltage-dependent calcium channel antagonist nifedipine. Eight conscious, chronically tracheotomized dogs received a low sodium diet (0.5 mmol Na·kg body wt-1·day-1). The dogs were studied twice in randomized order, either with nifedipine infusion (1.5 µg·kg body wt-1·min-1, Nifedipine) or without (Control). The dogs were breathing spontaneously: first hour, normoxia [inspiratory oxygen fraction (FiO2)=0.21]; second and third hour hypoxia (FiO2=0.1). In Controls, PRA (6.8±0.8 vs. 3.0±0.5 ngAngI·ml-1·min-1), AngII (13.3±1.9 vs. 7.3±1.9 pg/ml), and PAC (316±50 vs. 69±12 pg/ml) decreased during hypoxia (P<0.05). In Nifedipine experiments, PRA (6.5±0.9 vs. 10.5±2.4 ngAngI·ml-1·min-1) and AngII (14±1.1 vs. 18±3.9 pg/ml) increased during hypoxia, whereas the decrease in PAC (292±81 vs. 153±41 pg/ml) was blunted (P<0.05). These results foster the idea that the hypoxia-induced decrease in PRA involves L-type calcium channel activity.

Ograniczanie wyników

1 Journal of Physiology and Pharmacology

1 Arntz E.

1 Boemke W.

1 Hohne C.

1 Kaczmarczyk G.

1 Krebs M. O.

1 2003

Wyniki wyszukiwania

Nifedipine inhibits the hypoxia-induced decrease in plasma renin activity in conscious dogs