Haywood G P, Isaia J, Maetz J
Am J Physiol. 1977 Mar;232(3):R110-5. doi: 10.1152/ajpregu.1977.232.3.R110.
In isolated trout heads, perfused at constant pressure, epinephrine (10(-6) M) was found to double water and urea efflux but increased Ringer perfusion rate by only 33%. Drastic changes in perfusion rate (by clamping) produced smaller changes of both efflux rates. Epinephrine-stimulated increase in water and urea efflux, and perfusion rate, was blocked by propranolol (beta-blocker) but not by phentolamine (alpha-blocker). Both blockers together canceled out all epinephrine effects. Epinephrine increased water influx across isolated unperfused gill arches, the effect again being blocked by propranolol but not by phentolamine. Both blockers together canceled any epinephrine effect. We conclude that epinephrine alters branchial vascular flow and functional surface area via alpha- and beta-adrenergic receptors, but also increases branchial permeability to water and probably urea, via beta-adrenergic receptors. To test the validity of the perfused head technique, water and urea efflux rates were compared with in vivo values.
在以恒定压力灌注的离体鳟鱼头中，发现肾上腺素（10⁻⁶ M）使水和尿素的流出量增加了一倍，但林格氏液灌注速率仅增加了33%。通过夹闭导致的灌注速率的剧烈变化，使两种流出速率的变化较小。肾上腺素刺激引起的水和尿素流出量以及灌注速率的增加，可被普萘洛尔（β受体阻滞剂）阻断，但不能被酚妥拉明（α受体阻滞剂）阻断。两种阻滞剂共同作用可消除肾上腺素的所有作用。肾上腺素增加了离体未灌注鳃弓的水流入量，这种作用同样可被普萘洛尔阻断，但不能被酚妥拉明阻断。两种阻滞剂共同作用可消除肾上腺素的任何作用。我们得出结论，肾上腺素通过α和β肾上腺素能受体改变鳃血管流量和功能表面积，但也通过β肾上腺素能受体增加鳃对水以及可能对尿素的通透性。为了检验灌注头技术的有效性，将水和尿素的流出速率与体内值进行了比较。
