Physiology & Behavior. Vol. 49, pp. 165-167. ©Pergamon Press plc, 1991. Printed in the U.S.A.
0031-9384/91 $3.00 + .00
Hyperoxia Increases Salt Intake in Spontaneously Hypertensive Rats (SHR) 1 R. BEHM, 2 K. R U C K B O R N A N D U. F R A N Z
Department o f Physiology, Wilhelm-Pieck-University, 2500 Rostock, Germany R e c e i v e d 5 July 1990
BEHM, R., K. ROCKBORN AND U. FRANZ. Hyperoxia increases salt intake in spontaneously hypertensive rats (SHR). PHYSIOL BEHAV 49(1) 165-167, 1991. --The effect of normobaric hyperoxia on voluntary salt intake was investigated in 20 sham-operated and 11 carotid body-denervated SHR. While in sham-operated SHR the saline intake was enhanced during the whole hyperoxic period, the carotid body-denervated rats showed an increase in salt appetite only on the second and third day of hyperoxia. Water intake was not significantly different in sham-operated and carotid body-denervated SHR. These findings, together with our previous results, suggest that chemoreceptor activity determines salt appetite but not water intake in SHR. Spontaneously hypertensive rats
Carotid body denervation
Salt intake
THE factors controlling the excessive salt appetite of SHR are not entirely understood. Various environmental factors and humoral systems have been postulated to contribute to this appetite (5-7). There is some evidence that the exaggerated salt intake of SHR is closely linked to their chemoreceptor activity (2). Both physiological and pharmacological stimulation of the carotid bodies lead to a sustained suppression of their voluntary salt intake (1,3). Denervation of the carotid bodies abolishes these effects (4). In a preliminary study, we recently demonstrated that exposure of conscious SHR to moderate hyperoxia (40%) causes a transient but significant increase in salt intake (2). To further clarify the role of the peripheral arterial chemoreceptors in sodium intake, we investigated the effect of normobaric hyperoxia on voluntary salt intake in sham-operated (SO) and carotid body-denervated (CBD) SHR.
Water intake
Normobaric hyperoxia
20 1/h. Carbon dioxide was absorbed by potassium hydroxide. The rats were subjected to consecutive 5-day periods of normobaric normoxia, hyperoxia (50%) and normoxia, respectively. About 4 weeks after surgery all rats were anaesthetized with a mixture of chloralose and urethane (70/200 mg/kg). To determine the arterial blood gas status a catheter was inserted into the right femoral artery for blood sampling. Results are expressed as means___ S.E.M. The differences between basic normoxic levels and those recorded on subsequent days were checked for significance with Student's t-test for paired data. They were considered significant if p
0031-9384/91 $3.00 + .00
Hyperoxia Increases Salt Intake in Spontaneously Hypertensive Rats (SHR) 1 R. BEHM, 2 K. R U C K B O R N A N D U. F R A N Z
Department o f Physiology, Wilhelm-Pieck-University, 2500 Rostock, Germany R e c e i v e d 5 July 1990
BEHM, R., K. ROCKBORN AND U. FRANZ. Hyperoxia increases salt intake in spontaneously hypertensive rats (SHR). PHYSIOL BEHAV 49(1) 165-167, 1991. --The effect of normobaric hyperoxia on voluntary salt intake was investigated in 20 sham-operated and 11 carotid body-denervated SHR. While in sham-operated SHR the saline intake was enhanced during the whole hyperoxic period, the carotid body-denervated rats showed an increase in salt appetite only on the second and third day of hyperoxia. Water intake was not significantly different in sham-operated and carotid body-denervated SHR. These findings, together with our previous results, suggest that chemoreceptor activity determines salt appetite but not water intake in SHR. Spontaneously hypertensive rats
Carotid body denervation
Salt intake
THE factors controlling the excessive salt appetite of SHR are not entirely understood. Various environmental factors and humoral systems have been postulated to contribute to this appetite (5-7). There is some evidence that the exaggerated salt intake of SHR is closely linked to their chemoreceptor activity (2). Both physiological and pharmacological stimulation of the carotid bodies lead to a sustained suppression of their voluntary salt intake (1,3). Denervation of the carotid bodies abolishes these effects (4). In a preliminary study, we recently demonstrated that exposure of conscious SHR to moderate hyperoxia (40%) causes a transient but significant increase in salt intake (2). To further clarify the role of the peripheral arterial chemoreceptors in sodium intake, we investigated the effect of normobaric hyperoxia on voluntary salt intake in sham-operated (SO) and carotid body-denervated (CBD) SHR.
Water intake
Normobaric hyperoxia
20 1/h. Carbon dioxide was absorbed by potassium hydroxide. The rats were subjected to consecutive 5-day periods of normobaric normoxia, hyperoxia (50%) and normoxia, respectively. About 4 weeks after surgery all rats were anaesthetized with a mixture of chloralose and urethane (70/200 mg/kg). To determine the arterial blood gas status a catheter was inserted into the right femoral artery for blood sampling. Results are expressed as means___ S.E.M. The differences between basic normoxic levels and those recorded on subsequent days were checked for significance with Student's t-test for paired data. They were considered significant if p
