TIlE CORRELATION BETWEEN SPONTANEOUS CON- TRACTIONS AND POSTJUNCTIONAL SUPERSENSI- TIVITY OF THE SMOOTH MUSCLE OF THE RAT VAS DEFERENS’

LEE, TONY J-F., DAVID P. WESTFALL AND WILLIAM \V. FLEMING: The correlation between spontaileous contractions and I)ostjunctional supersensitivity of the smooth muscle of the rat vas deferens. J. Pharmacol. Exp. Then. 192: 136-148, 1975. (‘hronic postganglionic denervation of the rat vas defenens produces an increase in the sensitivity of tile?fl vitro smooth muscle to norepinephrine, methoxamine, acetylcholine, potassium and electrical stimulation. The maximal contractile response to nonepinephnine and acetyicholine is increased but the maximal response to potassium on electrical stimula-non is not affected. In addition, the vas deferens becomes spontaneously active after des nervation. The spontaneous cont ractions a re not prevented by tet rodotoxin, phentolamine or atropine. The appearance and magnitude of the spontaneous contractions are tempo-rally correlated with the development of ostjunctional supersensitivity. At a given time after denervation there is a significant correlation between the magnitude of tile spontane-OtIS contractions and tile sensitivity to norepinephnine, i.e., the sensitivity to norepineph-rine being greatest in those tissues with the largest spontaneous contractions. There is a