Document Detail


Evidence for contribution of effector organ cellular responses to the biphasic dynamics of heat acclimation.
MedLine Citation:
PMID:  8847335     Owner:  NLM     Status:  MEDLINE    
Abstract/OtherAbstract:
The involvement of cellular processes in the biphasic dynamics of heat acclimation was studied. Key steps in the cholinergic signal transduction pathway for water secretion were measured in the submaxillary gland of acclimating [2-day short-term heat acclimation (STHA) and 30-day long-term heat acclimation (LTHA) at 34 degrees C] or acute heat-stressed (2 h at 40 degrees C) rats in vitro. Both the carbamylcholine (CCh)-induced maximal fractional rate and the total 86Rb+ efflux, reflecting K+ efflux and water transport, transiently decreased in STHA (P < 0.001). In LTHA, the total K+ efflux increased (P < 0.001), whereas the maximal fractional rate of efflux increased only slightly. During STHA, the density of the high-affinity binding site of the muscarinic receptors (MRs) increased by 50% and their affinity for the muscarinic antagonist [3H]-N-methylscopolamine decreased transiently by 87%. Basal cytosolic Ca2+ concentration ([Ca2+]i) decreased (P < 0.05), but the peak CCh-induced [Ca2+]i increase resembled the control values. In LTHA, MR density continued to increase (100%; P < 0.05), whereas affinity resumed control values. Basal and CCh-induced [Ca2+]i increases returned to control levels. We conclude that glandular cellular processes follow a biphasic pattern with major apparent changes attributable to events distal to the [Ca2+]i rise. This was further validated by employing heat stress, which produced qualitatively different effects on the MR profile with a decrease in 86Rb+ efflux comparable to STHA. Hence, although heat-induced changes in the proximal components of the signal transduction pathway may contribute to altered regulatory span, the predominant apparent cellular effect is on the distal part of the pathway.
Authors:
M Horowitz; P Kaspler; Y Marmary; Y Oron
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Publication Detail:
Type:  Journal Article; Research Support, Non-U.S. Gov't    
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  80     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  1996 Jan 
Date Detail:
Created Date:  1996-10-24     Completed Date:  1996-10-24     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:  77-85     Citation Subset:  IM    
Affiliation:
Department of Radiology, Hadassah Schools of Medicine and Dental Medicine, Hebrew University, Jerusalem, Israel.
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MeSH Terms
Descriptor/Qualifier:
Acclimatization / drug effects,  physiology*
Animals
Body Temperature Regulation / drug effects,  physiology
Calcium / metabolism
Carbachol / pharmacology
Cell Physiological Phenomena
Cells / drug effects
Hot Temperature*
Kinetics
Muscarinic Agonists / pharmacology
Muscarinic Antagonists / pharmacology
N-Methylscopolamine
Parasympatholytics / pharmacology
Rats
Receptors, Muscarinic / physiology
Rubidium Radioisotopes / diagnostic use
Scopolamine Derivatives / pharmacology
Signal Transduction / physiology
Submandibular Gland / cytology,  drug effects,  metabolism
Sweating
Chemical
Reg. No./Substance:
0/Muscarinic Agonists; 0/Muscarinic Antagonists; 0/Parasympatholytics; 0/Receptors, Muscarinic; 0/Rubidium Radioisotopes; 0/Scopolamine Derivatives; 13265-10-6/N-Methylscopolamine; 51-83-2/Carbachol; 7440-70-2/Calcium

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


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