Static exercise performed by conscious cats elicits increases in heart rate (HR), left ventricular systolic pressure (LVSP), and the maximal rate of left ventricular pressure development [LV(dP/dt)(max)]. The increased HR is mediated primarily by withdrawal of parasympathetic tone, whereas a β-adrenergic mechanism is responsible for the LV(dP/dt)(max) increase. In the present study the cardiovascular responses to static exercise in awake cats was recorded before and after α-adrenergic blockade. Pressure transducers were implanted into the left ventricle of cats who had been trained operantly to perform static exercise. Significant increases in LVSP, LV(dP/dt)(max) and HR occurred in all cats during static exercise before blockade. In contrast, α-adrenergic blockade (phentolamine, 2.5 mg/kg iv) abolished the exercise-induced increase in LVSP but did not prevent increases in HR and LV(dP/dt)(max). The cats performed fewer exercise bouts per day during α-blockade than when unblocked. We conclude that an α-adrenergic mechanism mediates the increase in LVSP in response to static exercise in conscious cats.
|Original language||English (US)|
|Journal||American Journal of Physiology - Regulatory Integrative and Comparative Physiology|
|State||Published - 1986|
ASJC Scopus subject areas
- Physiology (medical)