Effects of calcium and its antagonists on the canine mesenteric circulation.
Effects of calcium and its antagonists on the canine mesenteric circulation.
复制标题
钙及其拮抗剂对犬肠系膜循环的影响。
DOI：
10.1161/01.res.48.5.692
复制
发表时间：
1981
影响因子：
20.1
通讯作者：
Jacobson,ED
中科院分区：
文献类型：
--
作者：
Walus,KM;Fondacaro,JD;Jacobson,ED
我们研究了麻醉犬动脉内输注含氯化钙或钙拮抗剂的溶液时肠循环的循环和代谢反应。测量包括末端回肠的血流量、动静脉氧含量差、放射性标记微球在粘膜-粘膜下层的分布和腔内压力。计算的参数包括耗氧量和粘膜-粘膜下血流分数。钙拮抗剂，硝苯地平和地尔硫卓，增加肠血流量，主要是粘膜-粘膜下层，抑制肠蠕动，并没有改变氧消耗。因此，这两种药物似乎主要作用于阻力血管，而不增加营养循环。氯化钙（1.0-500.0 μ g/kg/min）具有轻度收缩作用;在1000.0 μ g/kg/min剂量下，氯化钙成为肠系膜循环中的扩张剂。地高辛可逆转最高剂量钙的扩张作用，提示Na+，K+-ATP酶参与。硝苯地平完全阻断钙引起的肠循环收缩，部分抑制去甲肾上腺素引起的收缩。对离体肠系膜动脉平滑肌的研究表明，硝苯地平放松KCl收缩条在存在外部钙和放松去甲肾上腺素收缩条在存在和不存在外部钙的情况下。这些体外研究结果表明，钙拮抗剂干扰钙从细胞内位点的释放以及钙的缓慢内向电流。
We studied circulatory and metabolic responses of the intestinal circulation to intraarterial infusions of solutions containing calcium chloride or calcium antagonists in anesthetized dogs. Measurements included blood flow to the terminal ileum, arteriovenous oxygen content difference, distribution of radiolabeled microspheres to the mucosal-submucosal compartment and intraluminal pressure. Calculated parameters included oxygen consumption and fractional mucosal-submucosal blood flow. Both calcium antagonists, nifedipine and diltiazem, increased intestinal blood flow, mainly to the mucosa-submucosa, depressed intestinal motility, and did not change oxygen consumption. Thus, both agents appear to act mainly on resistance vessels without increasing the nutrient circulation. Calcium chloride (1.0-500.0 microgram/kg per min) had a mild constrictor effect; at a dose of 1000.0 microgram/kg per min, calcium chloride became a dilator agent in the mesenteric circulation. The dilator effect of the highest dose of calcium was reversed by digoxin, suggesting the involvement of Na+,K+-ATPase. Nifedipine completely blocked calcium-induced constriction of the intestinal circulation and partly inhibited norepinephrine-induced constriction. Studies on isolated mesenteric arterial smooth muscle revealed that nifedipine relaxed KCl-contracted strips in the presence of external calcium and relaxed norepinephrine-contracted strips in both the presence and absence of external calcium. These in vitro findings suggest that calcium antagonists interfere with the release of calcium from intracellular sites as well as with the slow inward current of calcium.