Endothelin stimulates Na(+)-K(+)-ATPase activity by a protein kinase C-dependent pathway in rabbit aorta.
Incubation with endothelin (Endo) caused a time- and concentration-dependent increase in both ouabain-sensitive (OS) and ouabain-insensitive (OI) 86Rb+ uptake [half-maximal effective concentration (EC50) for OS component = 11 nM] in the rabbit aorta. Increase in the OS component [Na(+)-K(+)-adenosine triphosphatase (ATPase) activity] accounted for 70% of the 110% increase in total 86Rb+ uptake at a maximally effective concentration of Endo (100 nM). Protein kinase C (PKC) activator phorbol 12,13-dibutyrate (PDBU; 100 nM) increased total 86Rb+ uptake by 69%, with 42% of the increase in the OS component. Stimulation by Endo and PDBU was not additive. Staurosporine (STA; 100 nM) inhibited stimulation of total 86Rb+ uptake by Endo and PDBU by approximately 60%. With ouabain and STA added together, inhibition of Endo-stimulated total 86Rb+ uptake (90%) was greater than with either agent alone, suggesting that STA inhibits an OS as well as an OI component of 86Rb+ uptake. Stimulation of total 86Rb+ uptake by both Endo and PDBU were also inhibited by approximately 60% by the Na(+)-H+ exchange inhibitor 5-(N-ethyl-N-isopropyl)amiloride (EIPA). Endo-stimulated total 86Rb+ uptake was not further inhibited when ouabain was added together with EIPA, suggesting that Na(+)-H+ exchange is primarily linked to the OS component of 86Rb+ uptake. In contrast, Na(+)-K(+)-Cl- cotransport inhibitor bumetanide inhibited increases in total 86Rb+ uptake caused by Endo (30%) and PDBU (56%) due solely to its effects on OI 86Rb+ uptake. Results suggest that Endo stimulates Na(+)-K(+)-ATPase activity in rabbit aorta by activating PKC and Na(+)-H+ exchange.(ABSTRACT TRUNCATED AT 250 WORDS)
Gupta
S
S
Diabetes and Metabolism Unit, Boston University Medical Center, Massachusetts 02118.
Ruderman
N B
NB
Cragoe
E J
EJ
Sussman
I
I
D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D000470:Alkaloids / Q000494:pharmacology; D000818:Animals; D001011:Aorta / Q000201:enzymology* / Q000378:metabolism; D002034:Bumetanide / Q000494:pharmacology; D002352:Carrier Proteins / Q000037:antagonists & inhibitors; D016232:Endothelins / Q000494:pharmacology*; D007546:Isoquinolines / Q000494:pharmacology; D008297:Male; D008565:Membrane Proteins / Q000037:antagonists & inhibitors; D010042:Ouabain / Q000494:pharmacology; D015240:Phorbol 12,13-Dibutyrate / Q000494:pharmacology; D010879:Piperazines / Q000494:pharmacology; D047428:Protein Kinase Inhibitors; D011494:Protein Kinases / Q000502:physiology*; D011817:Rabbits; D012413:Rubidium / Q000493:pharmacokinetics; D028021:Sodium-Potassium-Chloride Symporters; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D019311:Staurosporine
D000470:Alkaloids; D002352:Carrier Proteins; D016232:Endothelins; D007546:Isoquinolines; D008565:Membrane Proteins; D010879:Piperazines; D047428:Protein Kinase Inhibitors; D028021:Sodium-Potassium-Chloride Symporters; D002034:Bumetanide; D015240:Phorbol 12,13-Dibutyrate; D010042:Ouabain; D019307:1-(5-Isoquinolinesulfonyl)-2-Methylpiperazine; D011494:Protein Kinases; D000254:Sodium-Potassium-Exchanging ATPase; D019311:Staurosporine; D012413:Rubidium