Long Term Heat Acclimation: Acquired Peripheral Cardiovascular Adaptations and their Stability under Multifactorial Stressors

With heat acclimation, effectors efficiency increases. In blood vessels this is exemplified by increased [force generation]/ [sympathomimetic signalling] ratio. Cellular adaptive responses may contribute to this effect; however, their persistence when additional stress is applied is yet unknown. The present investigation shows, in aged rats, that hypohydration, superimposed on heat acclimation blunt acclimation—induced increased force generation in aortic rings and α adrenergic sensitivity. Upon hypohydration, heat stress induces faster and more pronounced splanchnic vasoconstriction. This may suggest that adaptations at the signalling pathway can be subjected to rapid changes under multifactorial stress.