Central injection of physostigmine attenuates exercise-induced pressor response in conscious cats.
The effects of intracerebroventricular administration of physostigmine, a cholinesterase inhibitor, on the cardiovascular responses evoked by static voluntary exercise were investigated using conscious cats. Four cats were trained to press a bar (200-650 g) with one forelimb for at least 20 s. The changes in mean arterial pressure (MAP), heart rate (HR), and developed force during the first five trials in 30 min by each individual cat were averaged, and a mean of the four values was then calculated. After the cats exercised for 30 min, either artificial cerebrospinal fluid (CSF) or physostigmine (5 micrograms) was administered intracerebroventricularly. Before physostigmine, exercise trials by the cats increased MAP and HR by 17 +/- 3 mmHg and 42 +/- 4 beats/min, respectively. Administration of physostigmine did not alter the resting MAP and HR but attenuated the MAP and HR responses to exercise (5-30 min postphysostigmine: MAP = 8 +/- 3 mmHg, HR = 25 +/- 7 beats/min; 30-60 min postphysostigmine: MAP = 4 +/- 3 mmHg, HR = 19 +/- 8 beats/min). Intracerebroventricular administration of CSF had no effect on the cardiovascular responses to static exercise. Pretreatment with the muscarinic antagonist, atropine (25 micrograms icv), blocked the attenuating effects of subsequent intracerebroventricular administration of physostigmine. These results demonstrate that stimulation of central muscarinic receptors attenuates the cardiovascular responses to static exercise by conscious cats. In addition, the present study suggests that there is no tonic effect of central muscarinic receptors on the cardiovascular responses to voluntary exercise.
Ally
A
A
Department of Internal Medicine, University of Texas Southwestern Medical Center, Dallas 75235-9034, USA.
Hand
G A
GA
Mitchell
J H
JH
D000704:Analysis of Variance; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D002415:Cats; D002552:Cerebral Ventricles / Q000187:drug effects / Q000502:physiology*; D003216:Conditioning, Operant / Q000187:drug effects; D003243:Consciousness; D005552:Forelimb; D006339:Heart Rate / Q000187:drug effects*; D007276:Injections, Intraventricular; D009043:Motor Activity / Q000187:drug effects*; D015999:Multivariate Analysis; D005082:Physical Exertion; D010830:Physostigmine / Q000008:administration & dosage / Q000494:pharmacology*; D013997:Time Factors
D010830:Physostigmine