Effects of papaverine on carbachol- and high K⁺-induced contraction in the bovine abomasum

Abstract

The effects of papaverine on carbachol (CCh) -and high K+- induced contraction in the bovine abomasum were investigated. Papaverine inhibited CCh (1 µM) -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 µM. Changes in the extracellular Ca2+ from 1.5 mM to 7.5 mM reduced verapamil-induced relaxation in high K+-depolarized muscles, but papaverine-induced relaxation did not change. Futhermore, papaverine (30 µM) and NaCN (300 µM) 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.

Imidazole-induced contractions in bovine tracheal smooth muscle are not dependent on the cAMP pathway

“…In the bovine trachea, cAMP content was measured by enzyme immunoassay, as reported previously [ 7 ]. The trachea was incubated with imidazole (300 µ M) or vehicle for 10 min.…”

“…It is also well known that the trachea is one of the organ, which has animal species difference for drug reaction [ 11 , 19 ]. We have continued research on the agents related to signal transduction of cAMP and cGMP in bovine and porcine smooth muscle [ 6 , 7 , 8 , 9 ].…”