Effects of alterations in cell phenotype and hypokalemia on sodium-potassium pump activity in rabbit vascular smooth muscle

Little, PJ and Bobik, A (1985) Effects of alterations in cell phenotype and hypokalemia on sodium-potassium pump activity in rabbit vascular smooth muscle. Clinical and Experimental Hypertension, A7 11: 1563-1582. doi:10.3109/10641968509073610


Author Little, PJ
Bobik, A
Title Effects of alterations in cell phenotype and hypokalemia on sodium-potassium pump activity in rabbit vascular smooth muscle
Journal name Clinical and Experimental Hypertension   Check publisher's open access policy
ISSN 1064-1963
Publication date 1985-01-01
Sub-type Article (original research)
DOI 10.3109/10641968509073610
Volume A7
Issue 11
Start page 1563
End page 1582
Total pages 20
Publisher Informa Healthcare
Language eng
Subject 2724 Internal Medicine
1314 Physiology
Abstract We investigated in cell culture, how alterations in phenotype accompanying proliferation of rabbit aortic smooth muscle and chronic hypokalemia could affect the Na, K pump. Total rubidium-86 uptake as well as ouabain and frusemide-sensitive uptake into cells was measured in physiological salts solution (PSS), PSS containing 5% foetal calf serum and PSS containing foetal calf serum plus 15μM monensin. In physiological salts solution 90% of the rubidium-86 uptake into contractile or synthetic state cells was frusemide-sensitive and less than 8% ouabain-sensitive. Total and frusemide-sensitive rubidium-86 uptakes, measured in PSS or PSS containing foetal calf serum were similar in cells cultured and maintained in the contractile phenotype, cells in the synthetic phenotype and those which had recently reverted from the synthetic to contractile phenotype. When cells were sodium loaded in the presence of monensin and foetal calf serum, ouabain-sensitive rubidium-86 uptake was 50% higher in cells which were maintained in culture in the contractile phenotype. Frusemide-sensitive rubidium-86 uptake was similar in each cell phenotype. To examine how cell culture in hypokalemic media would affect the Na, K pump, we determined ouabain-sensitive rubidium-86 uptake in the presence of monensin plus foetal calf serum in cells incubated for 24 hours in low and normal potassium containing culture media. Ouabain-sensitive uptake was 20% higher in cells cultured in a 0.76mM potassium medium than i n those cultured i n 5.4mM potassium medium. Frusemide-sensitive rubidium-86 uptake was unaffected. These results demonstrate that 'maximal' Na, K pump activity in sodium-loaded cells is reduced when cells change from the contractile to synthetic phenotype. This reduction appears only very slowly reversible when cells revert from the synthetic to contractile phenotype. Prolonged hypokalemia increases 'maximal' activity of the Na, K pump.
Keyword Cell culture
Cell phenotype
Hypokalemia
Monensin
Ouabain
Sodium-potassium co-transport
Sodium-potassium pump
Vascular smooth muscle
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
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