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Objectives

Na+, K+ pump inhibition is known to delay the development of apoptosis in vascular smooth muscle cells (VSMC). This study examines Na+, K+ pump involvement in the regulation of VSMC macromolecular synthesis and proliferation.

Methods

DNA, RNA and protein synthesis in VSMC from the rat aorta was studied by the incorporation of [3 H]-labelled thymidine, uridine and leucine. Cell cycle progression was estimated by flow cytometry. Intracellular Na+ and K+ content and Na+, K+ pump activity were quantified as the steady-state distribution of 22 Na and 86 Rb and the rate of ouabain-sensitive 86 Rb uptake in Na+-loaded cells, respectively.

Results

Ouabain inhibited the Na+, K+ pump with a K i of 0.1 mmol/l. At concentrations less than 0.1 mmol/l, neither [Na+] i nor [K+] i was affected by ouabain; elevation of ouabain concentration sharply increased the [Na+] i/[K+] i ratio with a K 0.5 of approximately 0 …