Document Detail

Cardiovascular-sympathetic adjustments to nonexertional heat stress in mature and senescent Fischer 344 rats.
MedLine Citation:
PMID:  2076998     Owner:  NLM     Status:  MEDLINE    
The purpose of this study was to test the hypothesis that the cardiovascular-sympathetic nervous system adjustments during nonexertional heat stress are exaggerated in senescent (S, 24 mo) vs. mature (M, 12 mo) conscious unrestrained Fischer 344 rats. During two separate trials (48 h apart), each animal was exposed to an ambient temperature (Ta) of 42 degrees C until a colonic temperature (Tco) of 41 degrees C was attained and then cooled at a Ta of 26 degrees C until Tco returned to the initial control level. Trial 1: heart rate (HR), mean arterial blood pressure (MAP), and arterial plasma concentrations of norepinephrine (NE), epinephrine (E), and lactate (La) were similar between the S and M groups during the baseline (control) period. The absolute increases in HR, MAP, NE, and E from the control period to the end of heating were of similar magnitudes between groups; however, La increased more in the S than M animals (P less than 0.05). During recovery, the declines toward control levels for all variables were similar or even more rapid in the S vs. M animals (P less than 0.05). Trial 2: the changes in HR and MAP during heating were similar to those observed in trial 1 in both groups. Generally, NE and E control levels were elevated in both groups compared with those in trial 1. The absolute increases in NE during heating were similar to trial 1 in both groups, whereas E increased to a greater extent than in trial 1 in the S animals (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
K C Kregel; D G Johnson; C M Tipton; D R Seals
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Publication Detail:
Type:  Comparative Study; Journal Article; Research Support, U.S. Gov't, P.H.S.    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  69     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1990 Dec 
Date Detail:
Created Date:  1991-04-22     Completed Date:  1991-04-22     Revised Date:  2013-09-26    
Medline Journal Info:
Nlm Unique ID:  8502536     Medline TA:  J Appl Physiol (1985)     Country:  UNITED STATES    
Other Details:
Languages:  eng     Pagination:  2043-9     Citation Subset:  IM; S    
Department of Exercise and Sport Sciences, University of Arizona, Tucson 85721.
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MeSH Terms
Blood Pressure*
Body Temperature
Body Temperature Regulation*
Cardiovascular System / growth & development*
Epinephrine / blood
Heart Rate*
Hot Temperature
Lactates / blood
Norepinephrine / blood
Rats, Inbred F344
Stress, Physiological / physiopathology
Sympathetic Nervous System / growth & development*
Grant Support
Reg. No./Substance:
0/Lactates; 51-41-2/Norepinephrine; 51-43-4/Epinephrine

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine

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