The effect of cholecystokinin on proximal colon myocyte in guinea-pigs and its mechanism / 中华消化杂志

ABSTRACT

Objective To investigate the effect of cholecystokinin (CCK) on colon motility and its mechanism in development of irritable bowel syndrome via recording ionic channels currents and contraction of guinea-pig proximal colon. Methods The guinea-pigs (body weight ranged from 200 g to 250 g) were deprived of food, but not water, for 12 hours before experiment. The animal was sacrificed and 6 cm of proximal colon was obtained. The contractile activity of isolated proximal colon in 1 × 10-7 ,5 × 10-7 or 1 × 10-6 mol/L of CCK-8 solution was recorded. The impact of 1 × 10-7 , 5 × 10-7 and 1 × 10-6 mol/L of CCK-8 and 1 × 10-6 mol/L CCK-8 nifidipin on current of calcium activated potassium channel (IBKac) was detected with an EPC-10 amplifier and an image analysis software.Results In comparison with blank [(0. 68 ±0. 12) g], the amplitude of colon contraction in 1 × 10-7 ,5×10-7 and 1×10-6 mol/L of CCK-8 was increased by (15. 0±1.5)%,(28. 0±1.4)%, and (36.0±1.6) %, respectively ( n = 7, P = 0. 023,0. 005 and 0. 01 ), but there was no significant change of frequency. When exogenous stimulation at +60 mV, the current of IBKac was enhanced to (117. 45 ± 3.60)%, (125.42± 5. 30)% or (136. 98±6. 80)% in 10-7 ,5 × 10-7 or 10-6 mol/L of CCK-8,respectively, compared with controls (n= 7, P＜0.01 ). However, after adding nifidipin, the current of IBKca was reduced to (102.23±5.60)% in 10-6mol/L of CCK-8 at +60 mV when compared with controls (n=7, P= 1. 491 ). Conclusion CCK enhances proximal colonic motility by increasing Ca2+ influx and IBKac current, which is characterized by enhancement of amplitude of contraction.