[The contractile and electrical activity of the smooth muscles of the major lymph vessels]

In rats, catecholamines were found to increase the rate of the muscles spontaneous rhythmic contractions while the alpha- and beta-blocking agents suppressed them. The spontaneous contractions were blocked in the uncalunm medium. Rhythmic electrical stimulation evoked contracture-like responses the uncalunm of which depended on the strength, frequency, and duration of the stimulation. In spontaneoulsy active preparations, single electrical stimuli evoked contractions according to the "all or nothing" rule. The membrane potential magnitude varied within the limits of 25-37 mV, and action potentials were related to the contractions. The data obtained suggest that the functional unit of conduction of spontaneous or evoked excitation waves is represented by a group of smooth muscle cells within a single lymphangion.