Buanes T, Grotmol T, Landsverk T, Nafstad P, Raeder M G
University of Oslo, Institute for Experimental Medical Research, Norway.
Acta Physiol Scand. 1988 May;133(1):1-9. doi: 10.1111/j.1748-1716.1988.tb08374.x.
To elucidate why arterial pH and carbon dioxide (PaCO2) modify the pancreatic H+/HCO3- secretory response to secretin stimulation, experiments were performed on anaesthetized pigs, recording the effects of arterial pH and PaCO2 on exocrine H+/HCO3- secretion and on morphology of pancreatic duct cells. Duct cells contained numerous cytoplasmic vesicles at secretory rest. Their number more than doubled during elevation of PaCO2 from 5.5 to 11.0 kPa. At arterial pH 7.40, maximal secretin stimulation cleared the cytoplasm of duct cells of more than 90% of the vesicles. At high PaCO2, this was accompanied by doubling the basolateral plasma membrane area and a 30% higher secretion rate than at PaCO2 5.5 kPa. Lowering arterial pH to 7.0 more than halved the secretin-induced vesicle clearance of duct-cell cytoplasm as well as exocrine H+/HCO3- secretion and abolished the secretin-dependent basolateral membrane area changes. Supramaximal secretin stimulation did not reverse the inhibitory effect of severe metabolic acidosis on secretion. It is concluded that PaCO2 and arterial pH may modify the secretory response to secretin through determining the incorporation of cytoplasmic vesicle material into the basolateral plasma membrane of duct cells.
为阐明动脉血pH值和二氧化碳（PaCO2）如何改变胰腺对促胰液素刺激的H⁺/HCO₃⁻分泌反应，我们对麻醉猪进行了实验，记录动脉血pH值和PaCO2对外分泌H⁺/HCO₃⁻分泌及胰腺导管细胞形态的影响。在分泌静止状态下，导管细胞含有大量细胞质囊泡。当PaCO2从5.5 kPa升高到11.0 kPa时，其数量增加了一倍多。在动脉血pH值为7.40时，最大促胰液素刺激使导管细胞胞质中90%以上的囊泡清除。在高PaCO2时，这伴随着基底外侧质膜面积加倍，分泌率比PaCO2为5.5 kPa时高30%。将动脉血pH值降至7.0，促胰液素诱导的导管细胞胞质囊泡清除以及外分泌H⁺/HCO₃⁻分泌减少一半以上，并消除了促胰液素依赖的基底外侧膜面积变化。超最大剂量促胰液素刺激不能逆转严重代谢性酸中毒对分泌的抑制作用。结论是，PaCO2和动脉血pH值可能通过决定细胞质囊泡物质并入导管细胞基底外侧质膜来改变对促胰液素的分泌反应。
