Effects of verapamil, sodium nitroprusside and calcium deprivation on the phenylephrine-induced contraction of smooth muscle strips from the reticular groove of adult cattle.
The effects of verapamil, sodium nitroprusside and calcium deprivation on the smooth muscle strips from the floor of the reticular groove of adult cattle were studied. The mechanical activity of the muscle strip was recorded isometrically. Contraction was induced with phenylephrine (10(-6) mol/l) in Tyrode solution. Verapamil (10(-6) mol/l) produced a high inhibition of the response, phasic and tonic (P < 0.05). Sodium nitroprusside (10(-6) mol/l) reduced mainly the phasic contraction (P < 0.05). Deprivation of Ca2+ from extracellular medium produced a high inhibition of the tonic phase. This study indicates that the action of verapamil on the reticular groove smooth muscle may be partially related to blockade of calcium entry through voltage-dependent channels, opened during phenylephrine stimulation. However, the nitroprusside action could be attributed to effect on the extrusion of calcium.
Departamento de Toxicología y Farmacología, Facultad de Veterinaria, Universidad Complutense de Madrid.
M D
MD
San Andrés
T
T
Encinas
F
F
González
M L
ML
de Vicente
M I
MI
San Andrés
C
C
Rodríguez
D000818:Animals; D002118:Calcium / Q000172:deficiency / Q000502:physiology*; D002121:Calcium Channel Blockers / Q000494:pharmacology*; D002417:Cattle / Q000502:physiology*; D009119:Muscle Contraction / Q000187:drug effects; D009130:Muscle, Smooth / Q000187:drug effects / Q000502:physiology; D009599:Nitroprusside / Q000494:pharmacology*; D010656:Phenylephrine / Q000494:pharmacology; D012159:Reticulum / Q000187:drug effects* / Q000502:physiology; D014662:Vasoconstrictor Agents / Q000494:pharmacology; D014665:Vasodilator Agents / Q000494:pharmacology*; D014700:Verapamil / Q000494:pharmacology*
D002121:Calcium Channel Blockers; D014662:Vasoconstrictor Agents; D014665:Vasodilator Agents; D009599:Nitroprusside; D010656:Phenylephrine; D014700:Verapamil; D002118:Calcium