Figure 1. Spontaneous excitations in corpus cavernosum smooth muscles of the rabbit.

A large CCSM preparation exhibited bursting spontaneous contractions (Aa). Another preparation developed continuous contractions (Ab). In a small CCSM preparation, bursts of spontaneous depolarizations were generated (Ba). In a different preparation, continuous spontaneous depolarizations were generated (Bb). A small CCSM preparation exhibited spontaneous increases in [Ca²⁺]_i (C). In a smaller CCSM preparation which developed spontaneous contractions, transmural stimulation applied during a contracting phase initiated phasic relaxations (1st and 2nd stimuli, D). In contrast, stimulation applied during a period of relaxation evoked a phasic contraction (3rd stimulus) or initiated spontaneous contractions (4th stimulus, D). The scale bar on the right of Ab applies to both traces in A and the scale bar on the right of Bb refers to both traces in B.