Department of Biology, University of Ottawa, ON, Canada.
Respir Physiol Neurobiol. 2012 Oct 15;184(1):60-4. doi: 10.1016/j.resp.2012.07.022. Epub 2012 Jul 31.
In many teleost fish, catecholamines activate a red blood cell (RBC) Na+/H+ exchanger (βNHE), raising RBC intracellular pH to protect haemoglobin-O2 loading. The present study tested the hypothesis that RBC intracellular carbonic anhydrase (CA) contributes to this adrenergic response. The pH of rainbow trout (Oncorhynchus mykiss) blood was monitored continuously in vitro using blood flowing in a semi-closed loop or in vivo using an extracorporeal circulation. Addition or injection of isoproterenol activated the βNHE, causing blood pH to fall (in vitro ΔpH = -0.28±0.03 pH units, N=16; in vivo, -0.12±0.02 pH units, N=6). Both in vitro and in vivo, inhibition of RBC CA by acetazolamide significantly decreased the magnitude of the adrenergic response (in vitro, ΔpH=-0.22±0.02 pH units, N=16; in vivo, -0.02±0.01 pH units, N=6) as well as the rate of recovery of blood pH following the adrenergic response. These results support the hypothesis that RBC intracellular CA plays an important role in the RBC adrenergic response of rainbow trout, and fuel speculation that interspecific differences in RBC CA activity are associated with the magnitude of the RBC adrenergic response.
在许多硬骨鱼中，儿茶酚胺激活红细胞 (RBC) Na+/H+ 交换器 (βNHE)，提高 RBC 细胞内 pH 值以保护血红蛋白-O2 加载。本研究检验了 RBC 细胞内碳酸酐酶 (CA) 有助于这一肾上腺素能反应的假设。使用半封闭循环体外监测虹鳟鱼 (Oncorhynchus mykiss) 血液的 pH 值，或使用体外循环监测体内 pH 值。异丙肾上腺素的添加或注射激活了 βNHE，导致血液 pH 值下降（体外ΔpH = -0.28±0.03 pH 单位，N=16；体内，-0.12±0.02 pH 单位，N=6）。在体外和体内，RBC CA 的抑制通过乙酰唑胺显著降低了肾上腺素能反应的幅度（体外，ΔpH=-0.22±0.02 pH 单位，N=16；体内，-0.02±0.01 pH 单位，N=6）以及肾上腺素反应后血液 pH 值的恢复速度。这些结果支持 RBC 细胞内 CA 在虹鳟 RBC 肾上腺素能反应中起重要作用的假设，并推测 RBC CA 活性的种间差异与 RBC 肾上腺素能反应的幅度有关。
