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The physiology of chronic water deprivation in the California ground squirrel ( Spermophilus beecheyi ): relevance to natural populations
Author(s) -
Baudinette R. V.
Publication year - 1974
Publication title -
journal of zoology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.915
H-Index - 96
eISSN - 1469-7998
pISSN - 0952-8369
DOI - 10.1111/j.1469-7998.1974.tb03124.x
Subject(s) - biology , urine , ground squirrel , population , zoology , sodium , water balance , period (music) , urine sodium , endocrinology , ecology , squirrel monkey , chemistry , medicine , physics , geotechnical engineering , environmental health , organic chemistry , acoustics , engineering
Monthly analysis of plasma and urine was carried out in a natural population of the ground squirrel Spermophilus beecheyi. Ionic and osmotic concentration of the urine varied greatly with season, reflecting changes in water availability, diet, and perhaps adrenal gland activity. Plasma concentrations remained constant over the twelve month period. In laboratory tests, urine and plasma were analyzed in animals trapped in both summer and winter, and in two laboratory stocks; one maintained on saline solutions the other on minimal water for maintenance of weight. The comparison between field and laboratory suggested that minimal water and saline treatments of this type were more stressful than field conditions, even in this period of very low rainfall. Minimal water rations in the laboratory produced renal hypertrophy and changes in plasma osmotic concentrations, both conditions not found in summer field populations. Control ad libitum groups suggested a possible seasonal difference in urine sodium levels which should be considered in laboratory water balance testing. Although the commonly used indications of water economy in rodents may be valid for laboratory comparisons, these results indicate the difficulties in field interpretation.