[Role and mechanism of motilin in colonic motility disorder].

Objective: To explore the role and mechanism of motilin in colonic motility disorder.

Methods: A total of 20 male Wistar rats (180 - 200 g) were randomly divided into 2 groups: water avoidance stress (WAS, n = 10) and sham water avoidance stress (SWAS, n = 10). Rats were exposed to 1 h WAS or SWAS daily for 10 consecutive days. Motilin in plasma was measured by enzyme-linked immunosorbent assay (ELISA). Proximal colon circular smooth muscle cells (PCSM) were isolated by enzymatic digestion and L-type calcium currents (ICa(L)) recorded by patch-clamp techniques.

Results: The fecal pellets during 1 h WAS significantly increased (5.4 ± 1.0 vs 2.4 ± 0.7, P < 0.01, n = 10). The motilin in plasma had significant difference between WAS rats and SWAS rats ((135 ± 35) vs (89 ± 24) pg/ml, P < 0.01, n = 10). The ICa(L) of two rats had no significant difference. But 6 × 10(-5) mmol/L motilin increased ICa(L) more in WAS than in SWAS rats at 0 mV ((1.6 ± 0.4) vs (1.0 ± 0.3) pA/pF, P < 0.05, n = 10).

Conclusion: WAS leads to elevated motilin levels in plasma and active L-type Ca(2+) channels in colon. And it contributes to colonic motility disorder.