Myogenic electrical control activity in longitudinal muscle of human and dog colon.

Abstract

SUMMARY1. The myogenic electrical activities of longitudinal muscle cells of the dog and human colon were investigated using intracellular microelectrodes.2. The resting membrane potentials of dog and human longitudinal muscle cells at the serosal side of the muscle layer were -49-4 + 0-9 and -44-8 + 1.3 mV respectively.3. Spontaneous electrical activity consisted of electrical oscillations of 13-7 + 1 1 mV and 8-6 + 2-1 mV amplitude, and 19-8 + 1I0 cycles/min and 2641 + 1-6 cycles/min frequency for dog and human cells respectively.4. Spiking activity only occurred superimposed on the electrical oscillations; the mean rate of rise of spikes was -150 mV/s in the dog and -260 mV/s in human cells and that of the oscillations was -18 mV/s in the dog and -16 mV in human cells.5. Spiking activity was abolished by calcium influx blockers and 0;01 mM-calcium Krebs solution. The amplitude of the electrical oscillations was reduced to 0-2-1-0 mV 30 min after calcium influx blockade or 30 min in 0-01 mM-calcium Krebs solution.6. Because of the high frequency of the oscillation-spike complexes, there was summation of associated contractile events in such a way that contraction frequency corresponded to frequency of bursts of oscillations and not to the frequency of the individual oscillations.7. The resting membrane potential of the longitudinal muscle cells at the myenteric plexus side of the layer was -44-9 + 1I0 mV, significantly lower than at the serosal side. 8. A gradient in membrane potential and slow-wave amplitude exists in circular muscle of dog colon, with the highest value at the mucosal side (-68-4 and 28-1 mV respectively) and the lowest at the myenteric side (-62-5 and 8-6 mV) of the muscle layer.

Pacemaker activity and inhibitory neurotransmission in the colon of Ws/Ws mutant rats

“…In the human colon studied in vitro, slow-wave activity has different components and all contractile activity and action potentials were abolished by L-type calcium channel blockers (6,38). The HF slow-wave component is also sensitive to L-type calcium channel blockers (6). The LF component in the human colon still needs to be examined, but unpublished data from our laboratory show that nifedipine abolished all slowwave activity.…”

“…The upstroke of the slow-wave activity in the circular muscle of the canine colon persists in the presence of L-type calcium channel blockers although it is dependent on extracellular calcium (3,58). In the human colon studied in vitro, slow-wave activity has different components and all contractile activity and action potentials were abolished by L-type calcium channel blockers (6,38). The HF slow-wave component is also sensitive to L-type calcium channel blockers (6).…”

Effect of voltage and cyclic AMP on frequency of slow‐wave‐type action potentials in canine colon smooth muscle.

“…The electrical activity observed in Krebs solution was as reported previously (Chow & Huizinga, 1987;Huizinga et al 1991). In the current experiments, the control data for frequency and duration of the slow-wave-type action potentials were 5.5 + 01 c.p.m.…”

Saussurea Lappa Modulates Gastrointestinal Motility, Motilin and Cholecystokinin Expression in Ulcer Rats

“…Gastrointestinal myoelectric activity that is a sensitive index of gastrointestinal motility, comprises slow wave and spike activity (fast wave). Slow wave could influence the mechanical contraction by pacing and directing gastrointestinal contraction [17] , and the spike activity would improve gastrointestinal motility [18] . Besides, MMC observed in gastrointestinal tract during fasting is a vivid pattern recording electromechanical activity and it consists of four phases as follows: quiescence, irregular contractions, regular contractions with a duration of at least 2 to 3 minutes and migrating downwards in the gastrointestinal tract and transitional period [19] .…”

“…Organic lesions usually complicate with function disorder, so gastrointestinal motility interruption is the sign of duodenal ulcer and becomes one of probable mechanisms in some studies [17,18,19] .…”