Effects of papaverine on carbachol- and high Ksup(+)-induced contraction in the bovine abomasum
2015
Kaneda, T. (Nippon Veterinary and Life Science University, Musashino, Tokyo (Japan). School of Veterinary Medicine, Laboratory of Veterinary Pharmacology) | Saito, E. | Kanda, H. | Urakawa, N. | Shimizu, K.
The effects of papaverine on carbachol (CCh) -and high Ksup(+)- induced contraction in the bovine abomasum were investigated. Papaverine inhibited CCh (1 microM) -and KCl (65 mM) -induced contractions in a concentration-dependent manner. Forskolin or sodium nitroprusside inhibited CCh-induced contractions in a concentration-dependent manner in association with increases in the cAMP or cGMP contents, whereas papaverine increased cGMP contents only at 30 microM. Changes in the extracellular Ca sup(2+) from 1.5 mM to 7.5 mM reduced verapamil-induced relaxation in high Ksup(+)-depolarized muscles, but papaverine-induced relaxation did not change. Futhermore, papaverine (30 microM) and NaCN (300 microM) decreased the creatine phosphate contents. These results suggest that the relaxing effects of papaverine on the bovine abomasum are mainly due to the inhibition of aerobic energy metabolism.
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