Related Experiment Video
Updated: Jul 21, 2026
14:02
Ex Vivo Assessment of Contractility, Fatigability and Alternans in Isolated Skeletal Muscles
Published on: November 1, 2012
25.1K
[AMPLITUDE-FREQUENCY'S DEPENDENCE OF M-RESPONSE OF THE SKELETAL MUSCLE OF RATS WITH EXPERIMENTAL HYPERCORTICOIDIZM].
Rossiiskii Fiziologicheskii Zhurnal Imeni I.M. Sechenova
|November 24, 2015
Summary
Hypercorticoidism in rats impairs nerve signal transmission, increasing muscle response time and reducing signal amplitude. This suggests potential synaptic issues and altered muscle excitability under excess cortisol.
Area of Science:
- Neurophysiology
- Endocrinology
Context:
- Investigates the neuromuscular effects of hypercorticoidism, a condition of excess cortisol.
- Utilizes a rat model to simulate human endocrine disorders.
Purpose:
- To determine the impact of hypercorticoidism on the M-response of the tibialis anterior muscle.
- To analyze changes in muscle excitability and nerve signal transmission under elevated cortisol levels.
Summary:
- Hypercorticoidism significantly lengthens muscle chronaxie and latent periods, while reducing M-response amplitude.
- Increased stimulation frequency exacerbates M-response amplitude reduction in hypercorticoid rats.
- Evidence suggests initial partial synaptic blockade and altered excitability at low stimulation frequencies.
Impact:
- Provides insights into the neuromuscular complications associated with conditions like Cushing's syndrome.
- Highlights the detrimental effects of prolonged high cortisol on peripheral nerve function.
- Contributes to understanding the physiological basis of muscle weakness in endocrine disorders.
Related Concept Videos
01:22Muscle Stimulation Frequency
The contraction strength of muscles is regulated by motor neurons, which modulate the frequency of action potentials dispatched to the motor units based on the body's requirements. This process of varying the muscle stimulation frequency allows muscles to contract with a force that is precisely tailored to the needs of the moment, whether lifting a feather or a heavy box.
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
Wave summation
At low firing rates, motor neurons induce individual twitch contractions in muscle fibers. These twitches...
01:19Cushing Syndrome II: Pathophysiology
Cortisol production is normally governed by the hypothalamic–pituitary–adrenal (HPA) axis, which maintains hormonal balance through tightly regulated feedback mechanisms. Disruption of this regulatory system is central to the development of Cushing syndrome, whether the excess cortisol originates from external medications or internal pathology. Persistent cortisol elevation alters metabolism, immune function, and endocrine signaling, producing the characteristic clinical features of the...