Zatzman M L, South F E
Am J Physiol. 1981 Jul;241(1):R87-91. doi: 10.1152/ajpregu.1981.241.1.R87.
Studies with unanesthetized active (non-lethargic) marmots demonstrated circannual rhythms of renal function (clearances of p-aminohippurate, creatinine, and inulin), plasma osmolality, and plasma sodium and potassium concentrations. Effective renal plasma flow, glomerular filtration rate, the clearance of creatinine, and plasma potassium were highest in spring and lowest in the fall and winter. Plasma osmolality and plasma sodium concentrations tended to be highest during the winter months and lowest in the spring and summer. p-Aminohippurate excretion was shown to be a Tm-limited system.
对未麻醉的活跃（非嗜睡）土拨鼠进行的研究表明，其肾功能（对氨基马尿酸、肌酐和菊粉清除率）、血浆渗透压以及血浆钠和钾浓度存在年周期节律。有效肾血浆流量、肾小球滤过率、肌酐清除率和血浆钾在春季最高，在秋季和冬季最低。血浆渗透压和血浆钠浓度在冬季往往最高，在春季和夏季最低。对氨基马尿酸排泄被证明是一个肾小管最大分泌量限制系统。
