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Biological effects and genetic analysis of thermosensitivity in hypertension

Acute heat exposure is more lethal to spontaneously hypertensive mice (SHM) than to normal mice. By genetic breeding experiments, we have demonstrated that the gene responsible for thermosensitivity, defined as the rate of body temperature increase, segregates with an increment of blood pressure in the F2 generation, supporting the possibility that thermosensitivity is part of a locus involved in hypertension. This locus is responsible for 25% of the difference in blood pressure between normal mice and SHM. Although severe, acute heat exposure is more detrimental in hypertension, brief episodes of chronic, mild heat stress are beneficial in that they normalize basal blood pressure in SHM. After 35 days of chronic heat treatment, the blood pressure of hypertensive mice is indistinguishable from that of the normotensives. The molecular response to heat which is characterized by the induction of heat stress genes, is abnormal in hypertension. Accumulation of heat stress proteins (HSP70) and of their mRNA following heat exposure is greater in tissues from hypertensive animals. These higher levels of hsp70 mRNA are observed not only after whole body heat exposure but also after in vitro heat stress of isolated organs and cells, and are due to an increased transcriptional rate of hsp70 gene. Our results indicate that increased heat sensitivity is associated with high blood pressure. When heat sensitivity is modified by chronic heat exposure, which could lead to the development of thermotolerance, there is a decrease in blood pressure. Abnormalities in the heat shock response in hypertensive animals may be responsible for their increased heat sensitivity as a part of the expression of the environmental modulation of hypertension.
Date January 1989
CreatorsMalo, Danielle
PublisherMcGill University
Source SetsLibrary and Archives Canada ETDs Repository / Centre d'archives des thèses électroniques de Bibliothèque et Archives Canada
Detected LanguageEnglish
TypeElectronic Thesis or Dissertation
CoverageDoctor of Philosophy (Division of Experimental Medicine.)
RightsAll items in eScholarship@McGill are protected by copyright with all rights reserved unless otherwise indicated.
Relationalephsysno: 000912534, proquestno: AAINL52180, Theses scanned by UMI/ProQuest.

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