1. Academic Validation
  2. H1-receptor antagonist, tripelennamine, does not affect arterial hypoxemia in exercising Thoroughbreds

H1-receptor antagonist, tripelennamine, does not affect arterial hypoxemia in exercising Thoroughbreds

  • J Appl Physiol (1985). 2002 Apr;92(4):1515-23. doi: 10.1152/japplphysiol.00925.2001.
Murli Manohar 1 Thomas E Goetz Sarah Humphrey Tracy Depuy
Affiliations

Affiliation

  • 1 Department of Veterinary Biosciences, College of Veterinary Medicine, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801, USA. mmanohar@uiuc.edu
Abstract

It has been suggested that pulmonary injury and inflammation-induced histamine release from airway mast cells may contribute to exercise-induced arterial hypoxemia (EIAH). Because stress failure of pulmonary capillaries and EIAH are routinely observed in exercising horses, we examined whether preexercise administration of an H1-receptor antagonist may mitigate EIAH. Two sets of experiments, placebo (saline) and antihistaminic (tripelennamine HCl at 1.10 mg/kg iv, 15 min preexercise) studies, were carried out on seven healthy, exercise-trained Thoroughbred horses in random order 7 days apart. Arterial and mixed venous blood-gas and pH measurements were made at rest before and after saline or drug administration and during incremental exercise leading to maximal exertion at 14 m/s on 3.5% uphill grade for 120 s. Galloping at this workload elicited maximal heart rate and induced exercise-induced pulmonary hemorrhage in all horses in both treatments, thereby indicating that capillary stress failure-related pulmonary injury had occurred. In both treatments, EIAH, desaturation of hemoglobin, hypercapnia, and acidosis of a similar magnitude developed during maximal exertion, and statistically significant differences between the placebo and antihistaminic studies could not be demonstrated. The failure of the H1-receptor antagonist to modify EIAH significantly suggests that pulmonary injury-induced histamine release may not play a major role in bringing about EIAH in Thoroughbred horses.

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