[The level of cyclic nucleotides during spontaneous smooth-muscle contractions in the guinea pig].

The relationships between isotonic tension and changes in cAMP and cGMP levels was studied in isolated preparations of the guinea-pig taenia coli and myometrium during spontaneous contractions. No significant changes in cyclic nucleotide levels were detected at any stage of the spontaneous contraction-relaxation cycle. The finding suggests that these changes play no significant role in the regulation of spontaneous contractions of the taenia coli and myometrium. However, other data obtained suggests the possibility of combined actions of the cGMP and phosphatidylinositols in control of smooth muscle motility during muscarine stimulation.