Possible role of Na(+)-K(+)-ATPase in the regulation of human corpus cavernosum smooth muscle contractility by nitric oxide.
1. This study was designed to determine the role of sodium-potassium adenosine triphosphatase (Na(+)-K(+)-ATPase) in the regulation of human corpus cavernosum smooth muscle contractility by nitric oxide (NO). In addition, we determined if the modulation of Na(+)-K(+)-ATPase activity by NO is dependent on the increase in intracellular cyclic GMP concentration. 2. The effect of NO donors, sodium-nitroprusside (SNP) and S-nitroso-glutathione (S-NO-Glu), and a permeable cyclic GMP analogue, 8-bromo-cyclic GMP, on Na(+)-K(+)-ATPase activity (measured as ouabain-sensitive 86Rb-uptake) was studied in human cultured corpus cavernosum smooth muscle cells (HCCSMC). In addition, the effect of the cyclic GMP lowering agent, methylene blue, on NO-induced increase in Na(+)-K(+)-ATPase activity was studied. 3. SNP (1 microM) caused time-dependent increases in ouabain-sensitive Rb-uptake (33-72%) over 2-20 min in HCCSMC. The stimulation of ouabain-sensitive Rb-uptake by SNP was concentration-dependent (30 and 102% with 0.1 and 1 microM SNP, respectively). Similarly, significant increases in ouabain-sensitive Rb-uptake were obtained with 1 and 10 microM S-NO-Glu. In contrast, incubation of HCCSMC with 8-bromo-cyclic GMP (100 microM) did not increase ouabain-sensitive Rb-uptake. 4. S-NO-Glu induced-increase in intracellular cyclic GMP synthesis, but not the increase in ouabain-sensitive Rb-uptake, was completely inhibited by methylene blue in HCCSMC. 5. The Na(+)-K(+)-ATPase inhibitor, ouabain, caused a concentration-dependent increase in tension (0.5 to 2 fold) in tissues contracted with 15 mM KCl. SNP and S-NO-Glu caused a concentration-dependent relaxation (concentration required to cause half maximal relaxation (ED50) = 0.04 and 0.2 microM, respectively) of HCC strips contracted with 15 mM K+. Ouabain (0.1 to 10 microM) inhibited the response to SNP and S-NO-Glu by shifting the concentration-response curves to the right and preventing full smooth muscle relaxation.6. These results indicate that the activity of Na+-K+-ATPase modulates the contractility of HCC smooth muscle, and that NO stimulates Na+-K+-ATPase activity in HCCSMC independently of its ability to increase the intracellular cyclic GMP concentration. They also suggest that stimulation of Na+-K+-ATPase activity plays an important role in NO-induced relaxation of HCC smooth muscle
Gupta
S
S
Department of Urology, Boston University School of Medicine, MA 02118, USA.
Moreland
R B
RB
Munarriz
R
R
Daley
J
J
Goldstein
I
I
Saenz de Tejada
I
I
D002478:Cells, Cultured; D006152:Cyclic GMP / Q000031:analogs & derivatives / Q000378:metabolism / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D005978:Glutathione / Q000031:analogs & derivatives / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D008297:Male; D009119:Muscle Contraction / Q000502:physiology; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000201:enzymology / Q000502:physiology*; D009569:Nitric Oxide / Q000494:pharmacology*; D009599:Nitroprusside / Q000494:pharmacology; D009603:Nitroso Compounds / Q000494:pharmacology; D010042:Ouabain / Q000494:pharmacology; D010413:Penis / Q000201:enzymology / Q000502:physiology*; D012414:Rubidium Radioisotopes; D026422:S-Nitrosoglutathione; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors / Q000378:metabolism / Q000502:physiology*
D004791:Enzyme Inhibitors; D009603:Nitroso Compounds; D012414:Rubidium Radioisotopes; D009599:Nitroprusside; C016276:8-bromocyclic GMP; D009569:Nitric Oxide; D026422:S-Nitrosoglutathione; D010042:Ouabain; D000254:Sodium-Potassium-Exchanging ATPase; D005978:Glutathione; D006152:Cyclic GMP