Na+-K+ regulation in cultured vascular smooth muscle cell of the spontaneously hypertensive rat.
Na+-K+ passive transport and activity of the Na+ pump were examined in serially passed cultured vascular smooth muscle cells originating from spontaneously hypertensive (SH), Wistar-Kyoto (WKY), and Wistar (W) rats. Measurements included 22Na+ and 86Rb+ (K+ analogue) uptake and washout rate constants as well as intracellular Na+ and K+ levels. The aforementioned variables were studied in cells subjected to either 2 mM Ca2+ or Ca2+-deficient media. In 2 mM Ca2+ medium, SH rat cells demonstrated the highest exchange (uptake and washout) rate constants for Na+ and Rb+ (K+) among cells of the three rat strains. At this extracellular Ca2+ concentration, the Na+ pump activity of SH rat cells was higher than that of WKY rat cells and was not different from that of W rat cells. Incubation in Ca2+-deficient medium resulted in increased magnitudes of Rb+ washout and Na+ uptake rate constants in all cell preparations associated with elevated intracellular Na+ concentrations and augmented activity of the Na+ pump. Under this condition, cells derived from SH rats showed the highest Na+ uptake and Rb+ washout rate constants associated with the highest Na+ pump activity. The increase in intracellular Na+ level in Ca2+-deficient medium was the highest in SH rat cells. These findings show that innate membrane defects and the response of the Na+ pump to these abnormalities can be demonstrated in in vitro-grown vascular smooth muscle cells of the SH rat.
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002118:Calcium / Q000494:pharmacology; D002339:Carotid Arteries; D002478:Cells, Cultured; D006973:Hypertension / Q000378:metabolism*; D007473:Ion Channels / Q000378:metabolism; D007700:Kinetics; D008297:Male; D009131:Muscle, Smooth, Vascular / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D011868:Radioisotopes; D051381:Rats; D011919:Rats, Inbred Strains; D011921:Rats, Inbred WKY; D012413:Rubidium / Q000378:metabolism; D012964:Sodium / Q000378:metabolism*; D012979:Sodium Radioisotopes / Q000378:metabolism
D007473:Ion Channels; D011868:Radioisotopes; D012979:Sodium Radioisotopes; D010042:Ouabain; D012964:Sodium; D012413:Rubidium; D011188:Potassium; D002118:Calcium