Increase in Ca2+ (Mg2+)-ATPase activity induced by a molsidomine derivative (SIN-1 A) and nitroglycerin in microsomal fraction of guinea-pig thoracic aorta.
The amount of phosphoric acid liberated from ATP by Ca2+ (Mg2+)-ATPase in microsomal fraction of guinea-pig thoracic aorta decreased with decreasing concentrations of calcium ions from 20.0 to 2.5 mM in the mixture of the enzyme and substrate. When CaCl2 (2.5 mM) and MgCl2 (5.0 mM) were present in the substrate, both nitroglycerin (0.1 to 1.0 mM) and SIN-1 A (a molsidomine derivative, 0.05 to 1.0 mM) increased the liberated phosphoric acid in a concentration-dependent manner. The contractile tension of smooth muscle prepared from guinea-pig thoracic aorta, which was previously increased by the pretreatment with prostaglandin F2 alpha (5.0 microM), was relaxed by both nitroglycerin and SIN-1 A (0.01 to 100 microM each) in a concentration-dependent manner. From the results, it is assumed that the stimulation of Ca2+ (Mg2+)-ATPase [Ca2+-pump ATPase] activity induced by nitroglycerin and SIN-1 A in the microsome of thoracic aorta takes part in the relaxation of contractile tension in the tissue.
D000818:Animals; D001013:Aorta, Thoracic / Q000201:enzymology*; D017301:Ca(2+) Mg(2+)-ATPase; D002118:Calcium / Q000378:metabolism; D000252:Calcium-Transporting ATPases / Q000378:metabolism*; D015237:Dinoprost; D005260:Female; D006168:Guinea Pigs; D066298:In Vitro Techniques; D008297:Male; D008861:Microsomes / Q000201:enzymology*; D009119:Muscle Contraction / Q000187:drug effects; D009131:Muscle, Smooth, Vascular / Q000187:drug effects; D005996:Nitroglycerin / Q000494:pharmacology*; D009602:Nitrosamines / Q000494:pharmacology*; D010208:Papaverine / Q000494:pharmacology; D011460:Prostaglandins F / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*
D009602:Nitrosamines; D011460:Prostaglandins F; D014665:Vasodilator Agents; C006006:N-nitrosomorpholinoaminoacetonitrile; D015237:Dinoprost; D010208:Papaverine; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D005996:Nitroglycerin; D002118:Calcium