Publisher Summary This chapter discusses the pharmacology of smooth muscle tissue. There has been a growing interest in the mechanism of action of pharmacological drugs on smooth muscle at the cellular level. A great step in the study of drugs was the detection of the relation between tonus, spontaneous activity and phase shifts in the electric activity of smooth muscle fibers. Increase of the tonus of smooth muscle evoked by acetylcholine, physostigmine, pilocarpine and choline, is accompanied by depolarization of the cell membrane, an increase in frequency of the spikes and a steeper rise of the prepotentials. A dissociation between the excitatory process and contraction itself may also arise during inhibition of carbohydrate-phosphate exchange in the muscle fiber by 2, 4-dinitrophenol. The influence of acetylcholine on the biochemical state of the smooth muscle is also suggested by investigations showing that an increase in tonus under the influence of acetylcholine leads to an increased oxygen consumption by the smooth muscle fibers. It is observed that 2, 4-dinitrophenol interferes with the normal linkage of tonus alterations in smooth muscle and its electrical activity, whereas the occurrence of action potentials is not coupled with an increase in tonus.
