Carey H V
Department of Comparative Biosciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706.
Am J Physiol. 1990 Aug;259(2 Pt 2):R385-92. doi: 10.1152/ajpregu.1990.259.2.R385.
Seasonal variations in mucosal structure and transport function were examined in active and hibernating ground squirrel jejunum. Mucosal wet weight and protein content, villus height, and mucosal surface area were lowest in hibernators, increased in spring, peaked in summer, and declined in fall. Transepithelial electrical parameters and net Na+ and 3-O-methylglucose (3-OMG) absorption measured in flux chambers were greatly reduced in hibernator tissues tested at 7 degrees C compared with tissues from hibernators or active squirrels studied at 37 degrees C. At 37 degrees C, net Na+ and 3-OMG absorption normalized to serosal surface area was similar in tissues from all squirrels. When normalized to mucosal surface area, absorption in hibernators was greater than in spring or summer squirrels but was not significantly different from fall values. Absorption normalized to mucosal area was similar among spring, summer, and fall squirrels. Increases in short-circuit current evoked by mucosal addition of D-glucose or L-alanine were significantly greater in hibernators than in fall squirrels. These results demonstrate seasonal variations in mucosal structure and transport function in captive ground squirrels. Enhanced area-specific absorption in hibernator tissues at 37 degrees C may represent a compensatory response to pronounced mucosal atrophy that occurs during hibernation.
研究了活跃和冬眠地松鼠空肠黏膜结构和转运功能的季节性变化。冬眠动物的黏膜湿重、蛋白质含量、绒毛高度和黏膜表面积最低，春季增加，夏季达到峰值，秋季下降。与在37℃下研究的冬眠动物或活跃松鼠的组织相比，在7℃下测试的冬眠动物组织中，在通量室中测量的跨上皮电参数以及净Na⁺和3 - O - 甲基葡萄糖（3 - OMG）吸收大大降低。在37℃时，以浆膜表面积标准化的净Na⁺和3 - OMG吸收在所有松鼠的组织中相似。当以黏膜表面积标准化时，冬眠动物的吸收大于春季或夏季松鼠，但与秋季值无显著差异。春季、夏季和秋季松鼠之间以黏膜面积标准化的吸收相似。黏膜添加D - 葡萄糖或L - 丙氨酸引起的短路电流增加在冬眠动物中比在秋季松鼠中显著更大。这些结果证明了圈养地松鼠黏膜结构和转运功能的季节性变化。在37℃时冬眠动物组织中增强的面积特异性吸收可能代表对冬眠期间发生的明显黏膜萎缩的一种代偿反应。
