Houpt T R, Yang-Preyer H, Geyer J, Norris M L
Department of Physiology, College of Veterinary Medicine, Cornell University, Ithaca, New York 14853-6401, USA.
Am J Physiol. 1999 Apr;276(4):R1156-63. doi: 10.1152/ajpregu.1999.276.4.R1156.
When a pig is deprived of drinking water, a deficit of body water develops that is corrected when the pig drinks to satiation. If food is available during the deprivation, the stimulus to drinking is plasma hyperosmolality. Because of the delay in correction of plasma hyperosmolality as ingested water is slowly absorbed, it has been thought that a rapid inhibitory signal from the digestive tract is necessary to prevent overdrinking. This concept was tested by measuring changes in plasma osmolality before and during drinking after such deprivation and also after infusion of hypertonic saline. As drinking began, there was a rapid fall of plasma osmolality to levels insufficient to drive drinking by the time drinking ended. This fall of plasma hyperosmolality to subthreshold levels while the pig is drinking seems to make a rapid inhibitory control signal from the digestive tract unnecessary to terminate the drinking bout under these conditions.
当猪被剥夺饮用水时，会出现身体缺水的情况，而当猪饮水至饱足时，缺水状况会得到纠正。如果在缺水期间有食物供应，那么引发饮水的刺激因素就是血浆渗透压升高。由于摄入的水被缓慢吸收，血浆渗透压升高的纠正存在延迟，因此人们认为，消化道发出的快速抑制信号对于防止过度饮水是必要的。通过测量缺水后以及输注高渗盐水后饮水前后血浆渗透压的变化，对这一概念进行了测试。饮水开始时，血浆渗透压迅速下降，到饮水结束时，其水平已不足以驱动饮水。在猪饮水时血浆渗透压升高降至阈值以下，这似乎表明在这些情况下，消化道发出的快速抑制控制信号对于终止饮水行为并非必要。
