Voluntary wheel running and pacing-induced dysfunction in hypertension

Area of Science:

• Cardiovascular Physiology
• Exercise Science
• Pharmacology

Background:

• Spontaneously hypertensive rats (SHR) often exhibit cardiac dysfunction.
• Understanding the effects of exercise and pharmacological interventions on cardiac performance is crucial.

Purpose of the Study:

• To investigate if voluntary wheel running enhances myocardial tolerance to pacing stress in female SHR.
• To determine if direct adenylyl cyclase agonism with forskolin improves cardiac performance during pacing in SHR.

Main Methods:

• Female Wistar Kyoto (WKY) and spontaneously hypertensive rats (SHR) were studied.
• SHR were divided into sedentary (SHR-SED) and voluntary wheel running (SHR-WHL) groups.
• Left ventricular (LV) function was assessed using Langendorff preparations during pacing stress, with and without forskolin infusion.

Main Results:

• Voluntary wheel running in SHR led to cardiac enlargement but did not alter resting hemodynamics.
• Pacing stress similarly impaired cardiac function in all groups.
• Forskolin infusion significantly improved LV function across all experimental groups.

Conclusions:

• Voluntary wheel running does not confer protection against pacing-induced myocardial dysfunction in SHR.
• Direct adenylyl cyclase agonism via forskolin demonstrates a protective effect on cardiac function during stress.
• These findings underscore the critical role of a functional myocardial beta-adrenergic signaling pathway.