Mediators involved in the rat uterus contraction in calcium-free solution.
1. The effect of (Na+ + K+)-ATPase inhibitor ouabain (10(-5)-3 x 10(-4) M), and the (Ca2+ + Mg2+)-ATPase inhibitors vanadate (6 x 10(-6)-6 x 10(-4) M), oxytocin (2 x 10(-9)-4 x 10(-8) M, and prostaglandin F2 alpha (PGF2 alpha, 10(-7)-6 x 10(-6) M) were assayed on rat uterus incubated in Ca-free medium. 2. Vanadate, oxytocin and PGF2 alpha, but not ouabain, induced contractions in a dose-dependent way (ED50: 7.5 +/- 0.03 x 10(-5) M; 6.5 +/- 0.064 x 10(-9) M and 3.8 +/- 0.085 x 10(-7) M). 3. Vanadate (3 x 10(-4) M) and oxytocin (OT, 10 mU/ml = 2 x 10(-8) M)-induced tonic contraction were not modified by nifedipine (10(-10)-10(-6) M), monensin (10(-5)-3 x 10(-4) M) or amiloride (10(-5)-10(-3) M). 4. The intracellular calcium release inhibitors TMB-8 (10(-6)-10(-4) M) and dantrolene (3 x 10(-6)-10(-4) M), and the prostaglandin release inhibitor indomethacin (3 x 10(-8)-6 x 10(-5) M) relaxed the vanadate and OT-induced tonic contractions. 5. The calmodulin inhibitors trifluoperazine (3 x 10(-5)-3 x 10(-4) M), bepridil (10(-8)-3 x 10(-4) M), calmidazolium (10(-7)-10(-4) M) and W-7 (10(-7)-10(-5) M) also relaxed the vanadate and OT-induced tonic contractions. 6. Our results suggest that oxytocin and vanadate-induced contractions on rat uterus in Ca-free medium could be produced by release of prostaglandins and intracellular calcium, and mediated by calmodulin.
Fernandez
A I
AI
Departamento de Medicina, Facultad de Medicina, Oviedo, Spain.
Cantabrana
B
B
Hidalgo
A
A
D000818:Animals; D017301:Ca(2+) Mg(2+)-ATPase / Q000037:antagonists & inhibitors; D002118:Calcium / Q000378:metabolism / Q000502:physiology*; D000252:Calcium-Transporting ATPases / Q000037:antagonists & inhibitors; D002147:Calmodulin / Q000037:antagonists & inhibitors / Q000378:metabolism; D016861:Cyclooxygenase Inhibitors / Q000494:pharmacology; D004347:Drug Interactions; D005260:Female; D010121:Oxytocin / Q000494:pharmacology; D011247:Pregnancy; D051381:Rats; D011919:Rats, Inbred Strains; D000254:Sodium-Potassium-Exchanging ATPase / Q000037:antagonists & inhibitors; D014590:Uterine Contraction / Q000502:physiology*; D014638:Vanadates / Q000494:pharmacology
D002147:Calmodulin; D016861:Cyclooxygenase Inhibitors; D014638:Vanadates; D010121:Oxytocin; D017301:Ca(2+) Mg(2+)-ATPase; D000252:Calcium-Transporting ATPases; D000254:Sodium-Potassium-Exchanging ATPase; D002118:Calcium