Document Type

Thesis

Publication Date

Spring 5-5-2017

Advisor

Dr. Clark Cotton

Abstract

Hibernating animals undergo dramatic changes in metabolic rates during torpor. One of most notable changes in these animals is the ability to maintain blood pressure and perfuse certain organs. Consequentially, blood perfusion to the kidneys is greatly decreased and the ability to concentrate urine halts. However, about once a week, torpor is interrupted and the animal becomes active to rewarm itself about once a week. This activity induces rapid regeneration of the extracellular osmotic gradient of the kidney, and allows urine to be concentrated. Nonetheless, regaining the extracellular osmotic gradient creates a potentially fatal consequence to the kidney cells. To combat the adverse effects of regaining an osmotic gradient, the animals significantly increase protective mechanisms within their kidneys, such as heat shock proteins (HSP) and organic osmolytes. It is well known that these rapid changes occur during cold-seasons, and little research has been done to compare these protective mechanisms within hibernating animals during the summer. To address this question, we worked in conjunction with a previous researcher to compare the data that has been done on a typical hibernator (Ichtidomys Tridecimlineatus) to data of a non-hibernator (Rattus Norvegicus). Rattus Norvegicus was placed under various water intake regimes to facilitate changes in the vertical osmotic gradient of the kidney. We then measured renal expression of HSP70, papillary urea, sorbitol, and the glomerular filtration rate in response to changes in the vertical osmotic gradient. Experimental treatments led to expected changes in urine volume and concentration for the rats, and serum homeostasis was largely maintained. GFR significantly decreased in the dehydration groups compared to the 600mM sucrose groups. The expression of HSP70 was not significantly different in any of the rat groups, but there was increased sorbitol concentrations as papillary urea concentrations increased during combination treatment.

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