Intervention of two voltage-dependent calcium-entry pathways in the contractile response to acetylcholine and KCl in rat uterus.
The contractile response of rat uterine smooth muscle was investigated. Verapamil and diltiazem concentration-dependently relax the sustained contractions induced by KCl (56 mmol/l) or acetylcholine (10(-4) mol/l). This inhibitory effect was not not freely reversed by washing the tissue and subsequently no contractile response was obtained in depolarized tissue, but a lower biphasic response (phasic and tonic) to acetylcholine was observed. Addition of cumulative concentrations of CaCl2 (1.2-19.2 mmol/l) induced a partial recovery of the contractile response to acetylcholine or KCl, but addition of MgCl2 (1.2-19.2 mmol/l did not. When the channel was reactivated by a third addition of KCl or acetylcholine after treatment with Ca2+, both spasmogens-induced phasic contractions recovered towards the initial configuration but the tonic component was not restored under any conditions. No recovery of mechanical response could be observed after Mg2+ treatment.
Ivorra
M D
MD
Departamento de Farmacologia, Facultad de Farmacia, Universidad de Valencia, España.
Chuliá
S
S
Noguera
M A
MA
D'Ocon
M P
MP
D000109:Acetylcholine / Q000494:pharmacology*; D000818:Animals; D002118:Calcium / Q000502:physiology; D015220:Calcium Channels / Q000187:drug effects* / Q000502:physiology; D004110:Diltiazem / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D005260:Female; D008564:Membrane Potentials; D009126:Muscle Relaxation / Q000187:drug effects; D009130:Muscle, Smooth / Q000502:physiology; D011189:Potassium Chloride / Q000494:pharmacology*; D051381:Rats; D017208:Rats, Wistar; D014590:Uterine Contraction / Q000502:physiology*; D014599:Uterus / Q000187:drug effects*; D014700:Verapamil / Q000494:pharmacology
D015220:Calcium Channels; D011189:Potassium Chloride; D014700:Verapamil; D004110:Diltiazem; D000109:Acetylcholine; D002118:Calcium