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Effects of diuretic-induced hypovolemia/isosmotic dehydration on cardiorespiratory responses to hyperthermia and its physical treatment in rabbits.
Int J Hyperthermia 2006; 22(2):135-47IJ

Abstract

Under conditions of heat stress and hyperosmotic dehydration, both animals and humans reduce thermoregulatory evaporation and regulate deep body temperature at elevated levels. Regarding the mechanisms, the main role in producing these thermoregulatory changes during dehydration is attributed to the increased osmolality of body fluids, although the role of the decreased plasma volume without changes in plasma osmolality (hypovolemia/isosmotic dehydration) has not been so far investigated. There are also controversial experimental results regarding the effects of dehydration on heat stress-induced cutaneous vasodilation. Therefore, this paper studied the effects of hypovolemia/isosmotic dehydration on cardiorespiratory responses to hyperthermia and its physical treatment in 17 anaesthetized adult rabbits. The animals were divided into two groups: normovolemic group (NV; n = 10) and hypovolemic group (HV; n = 7). In the HV group, hypovolemia/isosmotic dehydration (decrease in plasma volume by 16.1 +/- 1.2%) was induced by furosemide (5 mg kg-1 i.v.) without change in measured plasma Na+ concentration. Hyperthermia (the rise in body temperature (BT) to 42 degrees C by a gradual body surface heating) caused significant increase in minute ventilation (VE) in both groups. However, VE values were significantly higher in the HV rabbits compared to the NV animals despite the lower breathing frequency (p < 0.05). The panting was absent in the HV rabbits at the BT of 42 degrees C, unlike the NV animals. From cardiovascular variables, the vasoconstrictor response in visceral (mesenteric) region during hyperthermia in hypovolemic/isosmotic animals was attenuated (p < 0.05), whereas the heat stress-induced cutaneous vasodilation was not influenced by hypovolemia. Recovery of the BT by body surface cooling was accompanied by further increase in VE in the NV group, whereas VE decreased (p < 0.05) in the HV animals. Cooling led to recovery of the cardiovascular parameters. There were found no significant cardiorespiratory differences between the groups (NV:HV) during cooling. The lower frequency of breathing and attenuation of the mesenteric vasoconstriction during exogenous hyperthermia are present not only during hyperosmotic dehydration induced by water deprivation, but they also occur under conditions of furosemide-induced isosmotic dehydration/hypovolemia in rabbits. The heat stress-induced cutaneous vasodilation regarding its biological importance was not influenced by hypovolemia/isosmotic dehydration. Therefore, it is suggested that hypovolemia alone is sufficient to produce described respiratory, thermoregulatory and cardiovascular changes in dehydrated rabbits during exogenous hyperthermia, whereas hyperosmolality is not a requisite.

Authors+Show Affiliations

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

Pub Type(s)

Journal Article

Language

eng

PubMed ID

16754597

Citation

Brozmanova, Andrea, et al. "Effects of Diuretic-induced Hypovolemia/isosmotic Dehydration On Cardiorespiratory Responses to Hyperthermia and Its Physical Treatment in Rabbits." International Journal of Hyperthermia : the Official Journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, vol. 22, no. 2, 2006, pp. 135-47.
Brozmanova A, Jochem J, Javorka K, et al. Effects of diuretic-induced hypovolemia/isosmotic dehydration on cardiorespiratory responses to hyperthermia and its physical treatment in rabbits. Int J Hyperthermia. 2006;22(2):135-47.
Brozmanova, A., Jochem, J., Javorka, K., Zila, I., & Zwirska-Korczala, K. (2006). Effects of diuretic-induced hypovolemia/isosmotic dehydration on cardiorespiratory responses to hyperthermia and its physical treatment in rabbits. International Journal of Hyperthermia : the Official Journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group, 22(2), pp. 135-47.
Brozmanova A, et al. Effects of Diuretic-induced Hypovolemia/isosmotic Dehydration On Cardiorespiratory Responses to Hyperthermia and Its Physical Treatment in Rabbits. Int J Hyperthermia. 2006;22(2):135-47. PubMed PMID: 16754597.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of diuretic-induced hypovolemia/isosmotic dehydration on cardiorespiratory responses to hyperthermia and its physical treatment in rabbits. AU - Brozmanova,Andrea, AU - Jochem,Jerzy, AU - Javorka,Kamil, AU - Zila,Ivan, AU - Zwirska-Korczala,Krystyna, PY - 2006/6/7/pubmed PY - 2006/7/13/medline PY - 2006/6/7/entrez SP - 135 EP - 47 JF - International journal of hyperthermia : the official journal of European Society for Hyperthermic Oncology, North American Hyperthermia Group JO - Int J Hyperthermia VL - 22 IS - 2 N2 - Under conditions of heat stress and hyperosmotic dehydration, both animals and humans reduce thermoregulatory evaporation and regulate deep body temperature at elevated levels. Regarding the mechanisms, the main role in producing these thermoregulatory changes during dehydration is attributed to the increased osmolality of body fluids, although the role of the decreased plasma volume without changes in plasma osmolality (hypovolemia/isosmotic dehydration) has not been so far investigated. There are also controversial experimental results regarding the effects of dehydration on heat stress-induced cutaneous vasodilation. Therefore, this paper studied the effects of hypovolemia/isosmotic dehydration on cardiorespiratory responses to hyperthermia and its physical treatment in 17 anaesthetized adult rabbits. The animals were divided into two groups: normovolemic group (NV; n = 10) and hypovolemic group (HV; n = 7). In the HV group, hypovolemia/isosmotic dehydration (decrease in plasma volume by 16.1 +/- 1.2%) was induced by furosemide (5 mg kg-1 i.v.) without change in measured plasma Na+ concentration. Hyperthermia (the rise in body temperature (BT) to 42 degrees C by a gradual body surface heating) caused significant increase in minute ventilation (VE) in both groups. However, VE values were significantly higher in the HV rabbits compared to the NV animals despite the lower breathing frequency (p < 0.05). The panting was absent in the HV rabbits at the BT of 42 degrees C, unlike the NV animals. From cardiovascular variables, the vasoconstrictor response in visceral (mesenteric) region during hyperthermia in hypovolemic/isosmotic animals was attenuated (p < 0.05), whereas the heat stress-induced cutaneous vasodilation was not influenced by hypovolemia. Recovery of the BT by body surface cooling was accompanied by further increase in VE in the NV group, whereas VE decreased (p < 0.05) in the HV animals. Cooling led to recovery of the cardiovascular parameters. There were found no significant cardiorespiratory differences between the groups (NV:HV) during cooling. The lower frequency of breathing and attenuation of the mesenteric vasoconstriction during exogenous hyperthermia are present not only during hyperosmotic dehydration induced by water deprivation, but they also occur under conditions of furosemide-induced isosmotic dehydration/hypovolemia in rabbits. The heat stress-induced cutaneous vasodilation regarding its biological importance was not influenced by hypovolemia/isosmotic dehydration. Therefore, it is suggested that hypovolemia alone is sufficient to produce described respiratory, thermoregulatory and cardiovascular changes in dehydrated rabbits during exogenous hyperthermia, whereas hyperosmolality is not a requisite. SN - 0265-6736 UR - https://www.unboundmedicine.com/medline/citation/16754597/Effects_of_diuretic_induced_hypovolemia/isosmotic_dehydration_on_cardiorespiratory_responses_to_hyperthermia_and_its_physical_treatment_in_rabbits_ L2 - https://www.tandfonline.com/doi/full/10.1080/02656730500531988 DB - PRIME DP - Unbound Medicine ER -