| Object: To investigate the influence of contractive activity of isolated antrum and proximal colon smooth muscle and role and clinical significants of Somatostatin(SS), Vasoactive Intestinal Polypeptide(VIP), Motilin(MTL), Substance P(SP) in gastrointestinal dysmotilit in diabetic rats.Methods: Twenty age-matched male Sprague-Dawley rats were divided into two groups: one for control(n=10) and the other for experimental diabetes(n=10). Diabetes was induced by single intraperitoneal injection (l00mg/kg body wt) of streptozotocin(STZ). The resting tension, the mean contratile amplitude and frequency of spontaneous changes and the reaction to acetycholine(Ach) of isolated longitudinal, circular antrum and proximal colon smooth muscle strips and SS, VIP, MTL, SP contents in plasma, antrum and proximal colon tissure extracts were measured by transducer and radioimmunoassay respectively.Results: 1. In isolated circular muscle of antrum(AC), the resting tension and contratile frequency and Ach responses were significantly decreased in diabetic rats than those in controls (p<0.01). No significant differences of the mean contratile amplitude could be found in two groups (p>0.05 ) . In isolated longitudinal muscle of diabetic antrum(AL), the mean contratile amplitude and Ach responses were lower than in lean controls(p<0.01), while the resting tension and contratile frequency did not differ from those in leancontrols (p>0.05 ) . In comparison with normal controls, we could confirm the significantly decreased the resting tension, mean contratile amplitude and frequency of spontaneous changes and contratile responses to Ach in isolated circular muscle preparations of diabetic proximal colon(PC) (p<0.05). In isolated longitudinal muscle of proximal colon(PL), the contratile frequency and mean amplitude of spontaneous changes and contratile responses to Ach were significantly decreased in diabetic rats than those in normal rats(p<0.05). There was no statistical difference between diabetic rats and controls regarding the resting tension (p>0.05 ) . 2. The plasma levels of SS, VIP and MTL were higher in diabetic rats than those in controls(p<0.05), while SP contents was decreased(p<0.05). In the antrum, SS concentration was significantly higher in the diabetic rats than in lean rats(p<0.01). MTL and SP levels were lower in the diabetic rats than in lean controls(p<0.05). There was no statistical difference between diabetic rats and lean controls regarding the concentration of VIP( p>0.05 ). In the proximal colon, the levels of SS, VIP were significantly lower in the diabetic rats than in the controls rats(p<0.05). The concent of SP was higher than those of the controls in diabetic rats(p<0.05). The concentration of MTL in the diabetic rats did not differ from that in the lean controls( p>0.05 ). 3. there was an excellent correlation between the plasma SS concentration and the frequency of AC(r=-0.703, p<0.05) and the Ach responses of PC(r=-0.687, p<0.05) in diabetic rats. And there was a significant negative correlation between SS content of antrum and the resting tension of AC(r=-0.635, p<0.05) in diabetic rats. In diabetic rats, there was a significant negative correlation between the plasma VIP level and the frequency of AC (r=-0.667, p<0.05) and PC(r=-0.696, p<0.05). The VIP content of proximal colon in diabetic rats has a positive correlation with the mean amplitude of PL(r=0.744, p<0.05). Theconcentration of MTL in diabetic rats' plasma has a significant negative correlation with the mean amplitude of AL(r=-0.663, p<0.05) and the frequency of PL(r=-0.770, p<0.01), while in antrum, the MTL level has a positive correlation with the reaction to Ach of AC(r=0.947, p<0.01). As the plasma SP content in diabetic rats, it has an significant correlation with the Ach response of AC(r=0.635, p<0.05) and the mean amplitude of PL(r=0.695, p<0.05). There was an excellent correlation between the antrum SP level and the Ach response of AL(r=0.709, p<0.05) in diabetic rats.Conclusions: 1. Diabetes mellitus rat has gastroi... |
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