title: Effects of alpha-adrenergic blockade on cardiovascular responses to static exercise in cats.
abstract: 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 beta-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 alpha-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, alpha-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 alpha-blockade than when unblocked. We conclude that an alpha-adrenergic mechanism mediates the increase in LVSP in response to static exercise in conscious cats.
authors.forename: T G
authors.initials: TG
authors.lastname: Waldrop
authors.forename: M
authors.initials: M
authors.lastname: Bielecki
authors.forename: W J
authors.initials: WJ
authors.lastname: Gonyea
authors.forename: J H
authors.initials: JH
authors.lastname: Mitchell
mesh_terms: D000316:Adrenergic alpha-Agonists / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002319:Cardiovascular System / Q000187:drug effects*; D002415:Cats; D005260:Female; D006339:Heart Rate / Q000187:drug effects; D008297:Male; D010646:Phentolamine / Q000494:pharmacology*; D005082:Physical Exertion
chemical_list: D000316:Adrenergic alpha-Agonists; D010646:Phentolamine