Influence of gallopamil on the gastric effects of stress in conscious rats

The influence of the calcium-channel blocker gallopamil on cold-restraint stress (CRS)-induced gastric effects was investigated in conscious rats with gastric cannula. CRS, while leading to multiple gastric lesions, reduced gastric acid output and mast cell count, but increased the gastric emptying rate of acid solutions. Intraperitoneally injected gallopamil (1 mg/kg), given 1 h before CRS administration, prevented gastric lesion formation and partially reversed mast cell count and the emptying of acid solutions, but had no further effect on acid output. However, gallopamil in unrestrained rats did not significantly affect acid emptying or mast cell count. Regarding calcium involvement in the pathophysiology of stress-induced gastric lesions, the possible antiulcer actions of gallopamil involved in the prevention of CRS-induced lesion formation may be attributed to its putative stabilizing effect on mast cells and gastric emptying.

Cyclosporin A reduces the severity of cold-restraint-induced gastric lesions: role of leukocytes

The objective of this study was to determine the role of cyclosporin A (CsA) on cold-restraint-induced gastric lesions. Animals were subjected to 3 h immobilization at 4 degrees C in plastic restraining devices following a starvation period of 48 h. Gastric samples were obtained for the measurement of myeloperoxidase (MPO) activity, an index of number of peroxidase positive cells and thiobarbituric acid-reactive substances (TBARS; lipid peroxidation). Animals were pretreated with CsA which is a potent immunosuppressant and inhibits ischemia/reperfusion-induced polymorphonuclear leukocyte (PMN) infiltration. Cold-restraint administration significantly elevated the tissue MPO activity and TBARS formation. CsA pretreatment significantly reduced the severity of cold-restraint-induced gastric lesions while attenuating the elevated MPO measurements observed during cold-restraint administration. Animals rendered neutropenic with antineutrophil serum (ANS) exhibited significantly less gastric mucosal injury normally observed after cold-restraint stress. Neither CsA nor ANS treatment effected the elevated TBAR levels, indicating that PMNs are not involved in the lipid peroxidation process observed after cold-restraint stress. In conclusion, the results of this study indicate that CsA is capable of inhibiting cold-restraint-induced gastric mucosal injury and can attenuate the cold-restraint-induced increases in gastric MPO measurements. Our results also indicate that PMNs may be the important mediators of cold-restraint-induced gastric lesions.