Evidence for an enhanced transmembrane sodium (Na+) gradient induced by aldosterone in the incubated rat tail artery.
Aldosterone is known to stimulate Na+ transport as measured in terms of current-carrying capacity of epithelial sheets or of Na+ - K+ ATPase activity in cells. The possibility that this is reflected in an altered steady-state transmembrane Na+ distribution in vascular smooth muscle was here examined directly. Transmembrane Na+ and K+ gradients were first dissipated by overnight incubation in K-free physiological salt solution (PSS) at 10 degrees C and then reestablished by 3 hours in normal PSS at 37 degrees C. The addition of d-aldosterone (but not corticosterone) to these media significantly reduced cell Na. This involved only free cell Na which was reduced by about 20% of 3 mmole/kg dry wt. No significant change in membrane permeability measured in terms of net Li uptake at 3 degrees C or at 37 degrees C was observed. The lowest effective aldosterone concentration was 2.8 x 10(-9) M. These results are consistent with the observed enhancement of net Na+ transport in incubated arteries in DOCA-induced hypertension and in the SHR but do not account for the increased Na+ permeability observed in these states.
D000450:Aldosterone / Q000494:pharmacology*; D000818:Animals; D002199:Capillary Permeability / Q000187:drug effects*; D002463:Cell Membrane Permeability / Q000187:drug effects; D003345:Corticosterone / Q000494:pharmacology; D006973:Hypertension / Q000378:metabolism; D007700:Kinetics; D008094:Lithium / Q000378:metabolism; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D011188:Potassium / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D012964:Sodium / Q000378:metabolism*; D013623:Tail / Q000098:blood supply
D000450:Aldosterone; D008094:Lithium; D012964:Sodium; D011188:Potassium; D003345:Corticosterone