AJP - Gastrointestinal and Liver Physiology, Vol 242, Issue 2 124-G127, Copyright © 1982 by American Physiological Society
cAMP and calcium in generation of slow waves in cat colon
S. Anuras
Rhythmic oscillations in interactions between cAMP and calcium have been
proposed to account for a variety of rhythmic phenomena in cells. This idea
was investigated in relation to the rhythmic signals (electrical slow
waves) found in the electromyogram of the cat colon. A longitudinal strip
of muscularis propria from cat colon was studied in a superfusion bath that
allowed recording of the electromyogram from eight sites that were 2 cm
apart. The effect of increasing cAMP (by exposure of the tissue to cAMP,
dibutyryl cAMP, isobutylmethylxanthine, theophylline, caffeine, and
papaverine) was to reduce frequency and amplitude of slow waves and
duration of migrating spike bursts. All these maneuvers raised tissue cAMP
levels. Dibutyryl cGMP and cGMP had no effect. THe changes in slow waves,
but not migrating spike bursts, seen with raised cAMP levels were partly
reversed by raising the calcium concentration in the extracellular fluid.
Raising the extracellular sodium and potassium concentrations had no
effect. The results are consistent with the hypothesis that interactions
between cAMP and calcium are involved in slow-wave generation in colon
muscle.
