Exercise in Ponies: A Study of Myocardial Blood Flow, Coronary Vasodilator Reserve, Regional Distribution of Cardiac Output and Effects of Heart Rate on Coronary Flow

Transmural distribution of myocardial blood flow (MBF, 15 (mu)m diameter radionuclide labeled microspheres) was studied in 11 adult healthy ponies at rest {heart rate (HR) = 56 (+OR-) 4 beats.min('-1)}, during moderate (HR = 154 (+OR-) 3 beats.min('-1)) and severe (32 km.hr('-1), HR = 225 (+OR-) 7 beats.min('-1)) exercise performed on a treadmill. Coronary vasodilator reserve (CVR) was also examined in these animals using adenosine infusion at rest (4 (mu)M.kg('-1).min('-1)) and during severe exercise. Moderate exercise resulted in a marked increase in cardiac output, mean aortic pressure, right ventricular (RV) systolic and end-diastolic pressure (EDP), left ventricular (LV) EDP, LV max dP/dt, and a pronounced increase in trasmural MBF. Severe exercise resulted in further significant increments in all these variables. During severe exercise, endo:epi ratio for LV (0.99 (+OR-) 0.02) decreased significantly from control value (1.27 (+OR-) 0.03). With adenosine infusion during severe exercise, transmural MBF was able to further increase significantly. The data demonstrated that there remained a marked transmural CVR during severe exercise.

Name thesis:degree_name

Ph.D.

Level thesis:degree_level

Dissertation

Discipline thesis:degree_discipline

Veterinary Medical Science

Grantor

University of Illinois at Urbana-Champaign

Year dc:date

2014

Author dc:creator

• Parks, Christine Marie

• Biology, Veterinary Science

Identifier

(UMI)AAI8302955

OAI identifier oai:identifier

oai:www.ideals.illinois.edu:2142/71299