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Cardiac transfer function relating energy metabolism to workload in different species as studied with 31 P NMR
Author(s) -
Ligeti Laszlo,
Osbakken Mary D.,
Clark Bernard J.,
Schnall Mitchell,
Bolinger Lizann,
Subramanian Hari,
Leigh Jack S.,
Chance Britton
Publication year - 1987
Publication title -
magnetic resonance in medicine
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.696
H-Index - 225
eISSN - 1522-2594
pISSN - 0740-3194
DOI - 10.1002/mrm.1910040203
Subject(s) - heart rate , blood pressure , cardiology , medicine , in vivo , chemistry , anesthesia , biology , microbiology and biotechnology
Cardiac metabolism was studied with 31 P NMR in 7 dogs and 4 cats to determine whether animals adapted for different life‐styles (stalk and sprint vs endurance running) respond to increased work loads (heart rate × blood pressure product) with different high‐energy phosphate kinetics. Hearts were exposed via a left lateral thoracotomy under Nembutal anesthesia (40 mg/kg). Two‐turned solenoid surface coils were placed on the left ventricles; pacing wires were sutured into the left ventricular apeces. The femoral artery and vein were canulated for blood pressure and arterial blood gas monitoring and fluid and drug infusion, respectively. Animals were placed in a plexiglass holder into a 2.1‐T, 31‐cm‐bore, superconducting magnet. 31 P spectra were obtained from the heart using respiratory and electrocardiogram gating. Cardiac work loads were changed by pacing the heart at 4, 4.5, and 5 Hz. Heart rate × blood pressure product “work” was correlated with P i /PCr ratios. Dog hearts were more resistant than those of cats to changes in P i /PCr with increasing work load. It is possible that animals adapted to different life‐styles may have cardiovascular systems which are metabolically and mechanically adapted for different forms of stress. These differences may be elicited and effectively delineated using in vivo NMR techniques during various physiological interventions, such as pacing. The basis for these differences may be related to cardiac microvasculature or to intrinsic differences in enzyme kinetics. Delineation of these mechanisms may be helpful in the understanding of the physiological basis of cardiac function in health and disease. © 1987 Academic Press. Inc.