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Effects of hypovolemia on hypercapnic ventilatory response in experimental hyperthermia.
J Physiol Pharmacol. 2007 Nov; 58 Suppl 5(Pt 2):781-90.JP

Abstract

The present study was undertaken to evaluate the effects of hypercapnia on the cardiorespiratory control in normovolemic and hypovolemic rabbits during exogenous hyperthermia. Hypovolemia was induced by administration of furosemide, the body temperature (Tb) was gradually elevated to 42 degrees C by body surface heating. Subsequently, Tb was lowered back to the initial values by gradual cooling. Recordings were done at normothermia (TN=38 degrees C), during heating at 40 degrees C (TH1) and 42 degrees C (TH2), and in the course of Tb reverting toward the baseline values back at 40 degrees C (TC1), and finally after full return to the initial temperature value (TC2). The hypercapnic ventilatory response (HCVR) was estimated as the slope of minute volume (VE) on end-tidal CO2 (ETCO2) curves. We found that heating caused an increase in the VE slope in the normovolemic (NV), but not in hypovolemic (HV), rabbits. Between-group comparison revealed a significant increase in HCVR at TH2 and TC1 in NV vs. HV rabbits. Hypercapnia in hyperthermia (at TC2) was accompanied by a significant decrease in heart rate only in the hypovolemic group. Recovery of Tb was unaccompanied by appreciable changes in HCVR in either NV or HV groups. In the course of cooling, a decrease in heart rate during hypercapnic challenge was present in both group, in HV the drop was less prominent. We conclude that hypercapnia during heat stress in both normovolemic and hypovolemic rabbits is associated with altered cardiorespiratory responses. HCVR during exogenous hyperthermia is augmented in normovolemic, but not in hypovolemic, rabbits.

Authors+Show Affiliations

Department of Physiology, Jessenius Faculty of Medicine, Comenius University, Martin, Slovakia. zila@jfmed.uniba.skNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

18204192

Citation

Zila, I, et al. "Effects of Hypovolemia On Hypercapnic Ventilatory Response in Experimental Hyperthermia." Journal of Physiology and Pharmacology : an Official Journal of the Polish Physiological Society, vol. 58 Suppl 5, no. Pt 2, 2007, pp. 781-90.
Zila I, Brozmanova A, Javorka M, et al. Effects of hypovolemia on hypercapnic ventilatory response in experimental hyperthermia. J Physiol Pharmacol. 2007;58 Suppl 5(Pt 2):781-90.
Zila, I., Brozmanova, A., Javorka, M., Calkovska, A., & Javorka, K. (2007). Effects of hypovolemia on hypercapnic ventilatory response in experimental hyperthermia. Journal of Physiology and Pharmacology : an Official Journal of the Polish Physiological Society, 58 Suppl 5(Pt 2), 781-90.
Zila I, et al. Effects of Hypovolemia On Hypercapnic Ventilatory Response in Experimental Hyperthermia. J Physiol Pharmacol. 2007;58 Suppl 5(Pt 2):781-90. PubMed PMID: 18204192.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of hypovolemia on hypercapnic ventilatory response in experimental hyperthermia. AU - Zila,I, AU - Brozmanova,A, AU - Javorka,M, AU - Calkovska,A, AU - Javorka,K, PY - 2008/3/28/pubmed PY - 2008/4/16/medline PY - 2008/3/28/entrez SP - 781 EP - 90 JF - Journal of physiology and pharmacology : an official journal of the Polish Physiological Society JO - J. Physiol. Pharmacol. VL - 58 Suppl 5 IS - Pt 2 N2 - The present study was undertaken to evaluate the effects of hypercapnia on the cardiorespiratory control in normovolemic and hypovolemic rabbits during exogenous hyperthermia. Hypovolemia was induced by administration of furosemide, the body temperature (Tb) was gradually elevated to 42 degrees C by body surface heating. Subsequently, Tb was lowered back to the initial values by gradual cooling. Recordings were done at normothermia (TN=38 degrees C), during heating at 40 degrees C (TH1) and 42 degrees C (TH2), and in the course of Tb reverting toward the baseline values back at 40 degrees C (TC1), and finally after full return to the initial temperature value (TC2). The hypercapnic ventilatory response (HCVR) was estimated as the slope of minute volume (VE) on end-tidal CO2 (ETCO2) curves. We found that heating caused an increase in the VE slope in the normovolemic (NV), but not in hypovolemic (HV), rabbits. Between-group comparison revealed a significant increase in HCVR at TH2 and TC1 in NV vs. HV rabbits. Hypercapnia in hyperthermia (at TC2) was accompanied by a significant decrease in heart rate only in the hypovolemic group. Recovery of Tb was unaccompanied by appreciable changes in HCVR in either NV or HV groups. In the course of cooling, a decrease in heart rate during hypercapnic challenge was present in both group, in HV the drop was less prominent. We conclude that hypercapnia during heat stress in both normovolemic and hypovolemic rabbits is associated with altered cardiorespiratory responses. HCVR during exogenous hyperthermia is augmented in normovolemic, but not in hypovolemic, rabbits. SN - 0867-5910 UR - https://www.unboundmedicine.com/medline/citation/18204192/Effects_of_hypovolemia_on_hypercapnic_ventilatory_response_in_experimental_hyperthermia_ L2 - http://www.jpp.krakow.pl/journal/archive/11_07_s5/pdf/781_11_07_s5_article.pdf DB - PRIME DP - Unbound Medicine ER -