Different mechanisms for K+-induced relaxation in various arteries

(K+)o can be increased under a variety of conditions including subarachnoid hemorrhage. The increase of (K+)o in the range of 5 ~ 15 mM may affect tensions of blood vessels and cause relaxation of agonist-induced precontracted vascular smooth muscle (K+-induced relaxation). In this study, effect of the increase in extracellular K+ concentration on the agonist-induced contractions of various arteries including resistant arteries of rabbit was examined, using home-made Mulvany-type myograph. Extracellular K+ was increased in three different ways, from initial 1 to 3 mM, from initial 3 to 6 mM, or from initial 6 to 12 mM. In superior mesenteric arteries, the relaxation induced by extracellular K+ elevation from initial 6 to 12 mM was the most prominent among the relaxations induced by the elevations in three different ways. In cerebral arteries, the most prominent relaxation was produced by the elevation of extracellular K+ from initial 1 to 3 mM and a slight relaxation wasp rovoked by the elevation from initial 6 to 12 mM. In superior mesenteric arteries, K+-induced relaxation by the elevation from initial 6 to 12 mM was blocked by Ba2+ (30 muM) and the relaxation by the elevation from 1 to 3 mM or from 3 to 6 mM was not blocked by Ba2+. In cerebral arteries, however, K+-induced relaxation by the elevation from initial 3 to 6 mM was blocked by Ba2+, whereas the relaxation by the elevation from 1 to 3 mM was not blocked by Ba2+. Ouabain inhibited all of the relaxations induced by the extracellular K+ elevations in three different ways. In cerebral arteries, when extracellular K+ was increased to 14 mM with 2 or 3 mM increments, almost complete relaxation was induced at 1 or 3 mM of initial K+ concentration and slight relaxation occurred at 6 mM. TEA did not inhibit Ba2+/-sensitive relaxation at all and NMMA or endothelial removal did not inhibit K+-induced relaxation. Most conduit arteries such as aorta, carotid artery, and renal artery were not relaxed by the elevation of extracellular K+. Among conduit arteries, trunk of superior mesenteric artery and basilar artery were relaxed by the elevations of (K+)o. These data suggest that K+-induced relaxation has two independent components, Ba2+-sensitive and Ba2+-insensitive one and there are different mechanisms for K+-induced relaxation in various arteries.

The Reasonability of Using Radical Surgery for Improving Survival Rate in Elderly Gastric Cancer Patient

Three hundred ninety potentially curative resections for an adenocarcinoma of the stomach were performed in the Surgical Department of Chonbuk National University Hospital between 1991 and 1995. Eighty-nine patients were over 65 years of age, and three hundred-one patients were under 65 years of age. Pre-operative risk factors were statistically common in the over 65-years-old group(p<0.0044). Among the risk factors, pulmonary dysfunction was the most common pre-operative risk factor in both age groups, but diabetes mellitus was statistically significant factor in the under 65-years-old group. The incidence of post-operative complications revealed no statistical difference between two groups, and diarrhea was the most common complication in both groups. The incidence of complications increased when the disease was in an advanced stage and we did an extended operation, including a gastrectomy and a lymphadenectomy, but there was no statistical difference between the two age groups. The 3-year survival rate was higher when we did a curative resection with a subtotal or a total gastrectomy with a D2 lymphadenectomy than when we did non-curative resection, but there was no statistical difference between the two age groups. Hence, a curative resection including a radical gastrectomy with a D2 lymphadenectomy, if it is indicated, is reasonable approach for improving the survival rate in patients with an adenocarcinoma of the stomach, even elderly patients over 65 years of age.