Effects of 15-methyl prostaglandin F2alpha on isolated smooth muscles of guinea pig

In guinea pigs 15-methylprostaglandin F2alpha (MPGF) increased the tension of the smooth muscles with the pD2:uterus 7.7, oviduct 7.0, gastric fundus 6.9, ileum 6.8, gallbladder 5.5, and trachea 5.6. The effects of MPGF on all the preparations were attenuated by verapamil 34 microM, and the effects on 4 of the 6 preparations tested in Ca2+-free solution were also decreased. These results suggest that the excitatory action of MPGF on the isolated smooth muscles may be closely related to the Ca2+ influx. The effect of MPGF on gallbladder was not antagonized by atropine 1.4 microM, propranolol 3.4 microM, and phentolamine 27 microM, suggesting that the action of MPGF on gallbladder may not be mediated through autonomic receptors.