Biomaterial Database

Mechanical and metabolic performance of the rat heart: effects of combined stress of heat acclimation and swimming training. 1993

M Horowitz, and S Parnes, and Y Hasin

Division of Physiology, Hadassah School of Medicine, Hebrew University, Jerusalem, Israel.

Although the individual effects of heat acclimation and swimming exercise on cardiovascular reserve and efficiency have been studied, the relative and cumulative effects of these interventions have not. Myocardial developed force, coronary flow (CF), and oxygen consumption during baseline conditions and during pacing-induced tachycardia were therefore studied in isolated perfused hearts from four groups of rats: normothermic sedentary (C), heat acclimated sedentary (AC), normothermic swimmers (CS), and heat acclimated swimmers (ACS). Normothermic temperature was 24 degrees C. Heat acclimation was attained by continuous exposure to 34 degrees C for one and two months. Swimmers had two daily 75 minute sessions for five days a week with water temperatures of 33-35 degrees C and 36-38 degrees C for CS and ACS rats, respectively. After one month AC animals showed a remarkable decrease in O2 consumption. In contrast, ACS increased both O2 consumption and the maximal isometric force generated. After two months, O2 consumption of AC rats continued to be low. The heart failed to restitute the force developed at high pacing frequency. In these rats CF was remarkably low and remained unchanged with increased pacing. In contrast ACS maintained the ability to develop force at all pacing rates at a level similar to that of the normothermic C and ACS rat hearts, but at high oxygen cost. The data suggest that the AC heart is more efficient but cannot meet demands at high pacing rates. In contrast, swimming in the heat improved performance of ACS temporarily, without decreasing the metabolic rate.

UI	MeSH Term	Description	Entries
D008297	Male		Males
D009200	Myocardial Contraction	Contractile activity of the MYOCARDIUM.	Heart Contractility,Inotropism, Cardiac,Cardiac Inotropism,Cardiac Inotropisms,Contractilities, Heart,Contractility, Heart,Contraction, Myocardial,Contractions, Myocardial,Heart Contractilities,Inotropisms, Cardiac,Myocardial Contractions
D009206	Myocardium	The muscle tissue of the HEART. It is composed of striated, involuntary muscle cells (MYOCYTES, CARDIAC) connected to form the contractile pump to generate blood flow.	Muscle, Cardiac,Muscle, Heart,Cardiac Muscle,Myocardia,Cardiac Muscles,Heart Muscle,Heart Muscles,Muscles, Cardiac,Muscles, Heart
D010805	Physical Conditioning, Animal	Diet modification and physical exercise to improve the ability of animals to perform physical activities.	Animal Physical Conditioning,Animal Physical Conditionings,Conditioning, Animal Physical,Conditionings, Animal Physical,Physical Conditionings, Animal
D006321	Heart	The hollow, muscular organ that maintains the circulation of the blood.	Hearts
D006358	Hot Temperature	Presence of warmth or heat or a temperature notably higher than an accustomed norm.	Heat,Hot Temperatures,Temperature, Hot,Temperatures, Hot
D000064	Acclimatization	Adaptation to a new environment or to a change in the old.	Acclimation
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D013312	Stress, Physiological	The unfavorable effect of environmental factors (stressors) on the physiological functions of an organism. Prolonged unresolved physiological stress can affect HOMEOSTASIS of the organism, and may lead to damaging or pathological conditions.	Biotic Stress,Metabolic Stress,Physiological Stress,Abiotic Stress,Abiotic Stress Reaction,Abiotic Stress Response,Biological Stress,Metabolic Stress Response,Physiological Stress Reaction,Physiological Stress Reactivity,Physiological Stress Response,Abiotic Stress Reactions,Abiotic Stress Responses,Abiotic Stresses,Biological Stresses,Biotic Stresses,Metabolic Stress Responses,Metabolic Stresses,Physiological Stress Reactions,Physiological Stress Responses,Physiological Stresses,Reaction, Abiotic Stress,Reactions, Abiotic Stress,Response, Abiotic Stress,Response, Metabolic Stress,Stress Reaction, Physiological,Stress Response, Metabolic,Stress Response, Physiological,Stress, Abiotic,Stress, Biological,Stress, Biotic,Stress, Metabolic
D013550	Swimming	An activity in which the body is propelled through water by specific movement of the arms and/or the legs. Swimming as propulsion through water by the movement of limbs, tail, or fins of animals is often studied as a form of PHYSICAL EXERTION or endurance.