Document Detail

Selected contribution: chronic intermittent hypoxia enhances respiratory long-term facilitation in geriatric female rats.
MedLine Citation:
PMID:  12937027     Owner:  NLM     Status:  MEDLINE    
Age and the estrus cycle affect time-dependent respiratory responses to episodic hypoxia in female rats. Respiratory long-term facilitation (LTF) is enhanced in middle-aged vs. young female rats (72). We tested the hypothesis that phrenic and hypoglossal (XII) LTF are diminished in acyclic geriatric rats when fluctuating sex hormone levels no longer establish conditions that enhance LTF. Chronic intermittent hypoxia (CIH) enhances LTF (41); thus we further predicted that CIH would restore LTF in geriatric female rats. LTF was measured in young (3-4 mo) and geriatric (20-22 mo) female Sasco Sprague-Dawley rats and in a group of geriatric rats exposed to 1 wk of nocturnal CIH (11 vs. 21% O2 at 5-min intervals, 12 h/night). In anesthetized, paralyzed, vagotomized, and ventilated rats, time-dependent hypoxic phrenic and XII responses were assessed. The short-term hypoxic response was measured during the first of three 5-min episodes of isocapnic hypoxia (arterial Po2 35-45 Torr). LTF was assessed 15, 30, and 60 min postepisodic hypoxia. Phrenic and XII short-term hypoxic response was not different among groups, regardless of CIH treatment (P > 0.05). LTF in geriatric female rats was smaller than previously reported for middle-aged rats but comparable to that in young female rats. CIH augmented phrenic and XII LTF to levels similar to those of middle-aged female rats without CIH (P < 0.05). The magnitude of phrenic and XII LTF in all groups was inversely related to the ratio of progesterone to estradiol serum levels (P < 0.05). Thus CIH and sex hormones influence the magnitude of LTF in geriatric female rats.
A G Zabka; G S Mitchell; E B Olson; M Behan
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Publication Detail:
Type:  Journal Article; Research Support, U.S. Gov't, P.H.S.     Date:  2003-08-22
Journal Detail:
Title:  Journal of applied physiology (Bethesda, Md. : 1985)     Volume:  95     ISSN:  8750-7587     ISO Abbreviation:  J. Appl. Physiol.     Publication Date:  2003 Dec 
Date Detail:
Created Date:  2003-11-05     Completed Date:  2004-07-06     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:  2614-23; discussion 2604     Citation Subset:  IM    
Department of Comparative Biosciences, School of Veterinary Medicine, Madison, WI 53706, USA.
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MeSH Terms
Aging / physiology*
Anoxia / metabolism*
Apnea / metabolism
Blood Pressure / physiology
Caloric Restriction
Carbon Dioxide / metabolism
Estrous Cycle / physiology
Gonadal Steroid Hormones / blood
Hypoglossal Nerve / physiology
Oxygen Consumption / physiology
Phrenic Nerve / physiology
Rats, Sprague-Dawley
Respiratory Burst / physiology
Respiratory Mechanics / physiology*
Serotonin / physiology
Grant Support
Reg. No./Substance:
0/Gonadal Steroid Hormones; 124-38-9/Carbon Dioxide; 50-67-9/Serotonin

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