The Na+/K+ATPase mediates the alpha 1-adrenoceptor stimulated increase in 86Rb(+)-uptake in isolated ventricular cardiomyocytes from adult rat heart.
The aim of the present study was to identify the mechanism(s) responsible for the alpha 1-adrenoceptor stimulated increase in potassium uptake in ventricular cardiomyocytes isolated from adult rat heart. The Na+/K+ATPase blocker ouabain the Na+/K+/2Cl(-)-cotransporter blocker bumetanide, the Na+/H(+)-exchanger blocker HOE 694 and the potassium channel blocker 4-aminopyridine were used as experimental tools. 86Rb+ was used as potassium analogue. The basal 86Rb(+)-uptake rate was 0.25 +/- 0.01 ml/g protein x min. Maximal alpha 1-adrenoceptor stimulation increased the 86Rb(+)-uptake 38 +/- 2%. Ouabain dose dependently eliminated the alpha 1-adrenoceptor stimulated response with a -logIC50-value of 3.64 +/- 0.23. Bumetanide did not affect the stimulated response, and there was no effect of bumetanide on the ouabain sensitive component. HOE 694 and 4-aminopyridine had no effect on the stimulated 86Rb(+)-uptake. Ouabain and HOE 694 also dose dependently inhibited a portion of the basal 86Rb(+)-uptake (about 60% and 20%, respectively), but there was no effect of bumetanide or 4-aminopyridine on the basal 86Rb(+)-uptake. The results show that the Na+/K+ATPase alone mediates the alpah 1-adrenoceptor stimulated increase in potassium uptake in this preparation of ventricular cardiomyocytes isolated from adult rat heart.
Viko
H
H
Department of Pharmacology, University of Oslo, Norway.
Osnes
J B
JB
Skomedal
T
T
D015761:4-Aminopyridine / Q000494:pharmacology; D000818:Animals; D002034:Bumetanide / Q000494:pharmacology; D002301:Cardiac Glycosides / Q000494:pharmacology; D002478:Cells, Cultured; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D006146:Guanidines / Q000494:pharmacology; D006352:Heart Ventricles / Q000166:cytology / Q000378:metabolism; D008297:Male; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D010042:Ouabain / Q000494:pharmacology; D011188:Potassium / Q000378:metabolism*; D026902:Potassium Channel Blockers; D051381:Rats; D017208:Rats, Wistar; D018340:Receptors, Adrenergic, alpha-1 / Q000187:drug effects / Q000502:physiology*; D012413:Rubidium / Q000378:metabolism*; D012414:Rubidium Radioisotopes; D017923:Sodium-Hydrogen Exchangers / Q000494:pharmacology; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism* / Q000494:pharmacology; D013450:Sulfones / Q000494:pharmacology
D002301:Cardiac Glycosides; D004338:Drug Combinations; D006146:Guanidines; D026902:Potassium Channel Blockers; D018340:Receptors, Adrenergic, alpha-1; D012414:Rubidium Radioisotopes; D017923:Sodium-Hydrogen Exchangers; D013450:Sulfones; D002034:Bumetanide; C074107:3-methylsulfonyl-4-piperidinobenzoyl guanidine; D010042:Ouabain; D015761:4-Aminopyridine; D000254:Sodium-Potassium-Exchanging ATPase; D012413:Rubidium; D011188:Potassium