Effect of age on isoproterenol-induced maximal heart rate in horses

Thomas E. Goetz From the Departments of Veterinary Clinical Medicine (Goetz) and Veterinary Biosciences (Manohar), College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801.

Search for other papers by Thomas E. Goetz in
Current site
Google Scholar
PubMed
Close
 DVM
and
Murli Manohar From the Departments of Veterinary Clinical Medicine (Goetz) and Veterinary Biosciences (Manohar), College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, IL 61801.

Search for other papers by Murli Manohar in
Current site
Google Scholar
PubMed
Close
 BVSc, PhD

Click on author name to view affiliation information

SUMMARY

The effect of age on maximal heart rate induced by iv infusion of isoproterenol was studied in 19 healthy, sedentary, normothermic horses ranging in age from 0.25 to 9.90 years. Isoproterenol was administered iv (1.0 μg/kg of body weight/min) for 3 minutes, and the heart rate attained during the last 30 seconds of the infusion was determined. Linear regression of the maximal heart rate on age suggested that the rate decreased with age in a trend described by the equation: maximal heart rate (beats/min) = 209.63 − 3.28 × age (years). The regression coefficient (r) for this relation was 0.769 (P < 0.001). These data indicate that as healthy horses age, their β-adrenoceptor-mediated maximal chronotropic response is diminished.

SUMMARY

The effect of age on maximal heart rate induced by iv infusion of isoproterenol was studied in 19 healthy, sedentary, normothermic horses ranging in age from 0.25 to 9.90 years. Isoproterenol was administered iv (1.0 μg/kg of body weight/min) for 3 minutes, and the heart rate attained during the last 30 seconds of the infusion was determined. Linear regression of the maximal heart rate on age suggested that the rate decreased with age in a trend described by the equation: maximal heart rate (beats/min) = 209.63 − 3.28 × age (years). The regression coefficient (r) for this relation was 0.769 (P < 0.001). These data indicate that as healthy horses age, their β-adrenoceptor-mediated maximal chronotropic response is diminished.

All Time Past Year Past 30 Days
Abstract Views 0 0 0
Full Text Views 38 38 1
PDF Downloads 31 31 3
Advertisement