Altered spontaneous contractions of the ileum by anesthetic agents in rats exposed to peritonitis

AIM:To investigate in vitro effects of propofol,midazolam and dexmedetomidine,which are commonly used anaesthesic or sedatives,on spontaneous contractions of the ileum both in normal rats and those exposed to hyperdynamic peritonitis.METHODS:Spontaneous contractions of isolated ileum muscle segments from sham operated rats and those exposed to peritonitis,were studied in vitro.The amplitude and the frequency of spontaneous contractions of ileum muscle segments were studied after adding dexmetetomidine,propofol,and midazolam to the organ bath in a cumulative manner.RESULTS:Both amplitude(85.2±6.6 vs 47.4±7.1)and frequency(32.8±4.6 vs 20.2±3.9)of spontaneous contractions in ileum smooth muscle segments were decreased significantly in the peritonitis group compared to the control group(P<0.05).Dexmedetomidine significantly increased the amplitude of spontaneous contractions(85.2±6.6 vs 152.0±5.4,P<0.05)whereas,propofol(85.2±6.6 vs 49.6±4.8,P<0.05)and midazolam(85.2±6.6 vs 39.2±4.5,P<0.05)decreased it in both control and peritonitis groups.The frequency of spontaneous contractions were significantly decreased by propofol in both control(32.8±4.6 vs 18.2±3.4,P<0.05)and peritonitis groups 20.2±3.9 vs 11.6±3.2,P<0.05).Dexmedetomidine and midazolam did not cause significant changes in the number of spontaneous contractions in both control and the peritonitis groups(P>0.05).CONCLUSION:Propofol,midazolam and dexmedetomidine have various in vitro effects on spontaneous contractions of the rat ileum.While dexmedetomidine augments the spontaneous contraction of the rat ileum,propofol attenuates it.However,the effects of these compounds were parallel in both control and peritonitis groups.

Lack of nitrate tolerance in isosorbid dinitrate- and sodium nitroprusside-induced relaxation of rabbit internal anal sphincter

AIM: To investigate the tolerance development against the relaxant effect of nitric oxide donating drug isosorbide dinitrate (ISDN) and sodium nitropruside (SNP) in internal anal sphincter (IAS) smooth muscle. METHODS: Relaxation responses of ISDN, and electrical fi eld stimulation (EFS) were obtained before and after tolerance induction by ISDN incubation. RESULTS: ISDN (10-7-10-4 mol/L) and SNP (10-8-10-4 mol/L) caused a concentration-dependent relaxation on the basal tonus of the isolated rabbit IAS strips. After a period of 2 h incubation of the 6 x 10-4 mol/L ISDN the relaxation effects of ISDN and SNP did not change compared to control strips. EFS evoked frequency-dependent relaxation in internal anal sphincter smooth muscle and Emax obtained from control strips were not changed in ISDN tolerance-inducing condition. In this study nitrate tolerance was not observed in rabbit IAS smooth muscle. CONCLUSION: This result shows that nitric oxide donating drugs relaxes the internal anal sphincter of the rabbits without the development of tolerance.