Related Experiment Video
Updated: Aug 6, 2026

Skeletal Muscle Neurovascular Coupling, Oxidative Capacity, and Microvascular Function with 'One Stop Shop' Near-infrared Spectroscopy
Published on: February 20, 2018
Myocardial metabolism and performance in hypoxia: effect of epinephrine
Abstract:
Effects of epinephrine (10(-5) M) on mechanical performance, glycolysis, glycogenolysis, lipolysis, and metabolism of adenine nucleotides were studied in isolated hypoxic rabbit hearts. The exposure of hearts to hypoxia decreased their mechanical performance and heart rate, but increased their utilization of glucose by 50% and the release of lactate by 139%. Myocardial stores of glycogen and ATP declined by 53 and 84%, respectively, but their breakdown products such as lactate, pyruvate, AMP, and inosine accumulated in these hearts. Myocardial content of free fatty acids decreased, and the amount of glycerol increased in hypoxic hearts. Epinephrine stimulated mechanical performance and heart rate of hypoxic hearts, but decreased myocardial glycogen and ATP even more by 62 and 33%, respectively. Though glucose utilization remained unchanged, the release of lactate increased by 66% from hypoxic hearts treated with epinephrine. However, epinephrine failed to stimulate myocardial lipolysis in hypoxic hearts. These metabolic changes due to epinephrine would lead to accelerated depletion of energetic reserves in hypoxic heart and its earlier deterioration.
Related Concept Videos
Factors Influencing Heart Rate
Let us explore the significant factors affecting heart rate, including age, body temperature, posture, acute pain, chemical influences,...
Exercise and Muscle Performance
Endurance exercises
Endurance exercises involve running, swimming, or cycling, which require repetitive movements with low force output. When a person engages in endurance exercise, a few noticeable changes occur in their skeletal muscles. For instance, the number of capillaries...
Pathophysiology of Cardiac Performance
Exercise and Cardiac Output
Sustained exercise increases the muscles' oxygen demand, which can be met...
Exercise and Cardiovascular Response
Light to moderate physical activity initiates a series of interconnected responses in the body. The heart rate modestly increases in anticipation of the workout, followed by widespread vasodilation as oxygen consumption by skeletal muscles increases. This results in decreased peripheral resistance, increased capillary blood flow, and accelerated...
Cardiac Output I:Effect of Heart Rate on Cardiac Output
Cardiac output (CO) refers to the total amount of blood ejected by one of the ventricles in liters per minute (L/min). In a resting adult, CO ranges from 5 to 6 L/min, adjusting according to the body's metabolic requirements.
Effect of Heart Rate on Cardiac Output
Cardiac output adapts to metabolic demands during stress, physical activity, or illness. The autonomic nervous system regulates heart rate via the sinoatrial node. The parasympathetic nervous system decreases heart rate...

