Gastric Smooth Muscle Essay

Gastrointestinal motility and the contraction of the surrounding smooth muscles heavily depend on the rhythmicity of the depolarization that occurs during a slow wave potential. These slow wave potentials allow for the contraction of smooth muscle, squeezing the stomach and the intestines (Helden et al., 2010). Slow wave potentials are suggested to be propagated by the spontaneous electrical activity generated by the interstitial cells of Cajal. These interstitial cells are found within the gastric smooth muscles and are distributed throughout the gastrointestinal tract between the esophagus and the internal anal sphincter (Sanders et al., 2009). Slow waves are composed of two fundamental elements: electronic propagation of pacemaker potentials …show more content…
Effects causing a change in the resting membrane potential, RMP, of the gastric smooth muscle can affect the depolarization of electronic propagation leading to a change in the excitability of slow wave potentials (Ahn et al., 2015). Both voltage-dependent and voltage-independent Potassium, K+, channels can be involved in deciding the RMP of the gastric smooth muscle (Ahn et al., 2015). The voltage-dependent K+ channels consist of large-conductance Ca2+-activated K+ channels (BK) and delayed rectifying K+ channels (Kv) (Ahn et al., 2015). The voltage-independent K+ channels consist of small-conductance Ca2+-activated K+ channels (SK), ATP-sensitive K+ channels (KATP), and inward rectifying K+ channels (Kir) (Ahn et al., 2015). The effects of these channels and their inhibitors were studied to determine how they affect the RMP of the gastric smooth muscle. Results suggested that BK channel blockers did not affect the RMP while the Kv channels did. SK channels, KATP channels and Kir channels and their blockers also affected the RMP. The authors study is justified based on their findings and …show more content…
BK channel blockers, tetraethylamonium chloride and charybdotoxin, resulted in a negligible effect on the RMP of gastric smooth muscle and its SWP (Ahn et al., 2015). Kv channel blocker, 4-aminopyridine, was used and induced depolarization of the RMP (Ahn et al., 2015). KATP channel blocker, Apamin, and Kir channel activation from low Barium, Ba2+, concentrations, were used and both induced depolarization of RMP (Ahn et al., 2015). The author’s results involving the SK channel and its inhibitor, Apamin, are not consistent throughout the current study. Initially, it is stated that the SK channel and its inhibitor, Apamin, induced depolarization suggesting that it does have an effect on the RMP and SWP of gastric smooth muscle (Ahn et al., 2015). In contrast to this, the graphical representation of Apamin shows no effect on the RMP and SWP of the smooth muscle and the discussion states that SK channels have a negligible effect on the RMP (Ahn et al., 2015). A study involving SK channels and its effects on the smooth muscle of the bladder clarifies the inconsistent results found in the current study. Isolation of fresh human tissue and patch-clamp recordings were used in both studies. An SK channel activator was used to induce the hyperpolarization of the RMP causing contraction of the smooth muscle in the bladder. Apamin extirpated the hyperpolarizing effect of the SK

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