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Ability of L-histidine to decrease desensitization of the myometrium to epinephrine.
T V Tumanova1, E N Sizova, V I Tsirkin
1Department of Normal Physiology, Kirov State Medical Academy.
Bulletin of Experimental Biology and Medicine
|January 25, 2005
Summary
Histidine prevents beta-adrenoceptor desensitization in rat uterine horns. This amino acid potentiates receptor activation and may improve therapies using beta-adrenoceptor agonists.
Area of Science:
- Pharmacology
- Physiology
- Biochemistry
Background:
- Beta-adrenoceptors mediate smooth muscle relaxation.
- Epinephrine can cause beta-adrenoceptor desensitization, reducing its efficacy.
- Understanding modulators of receptor desensitization is crucial for therapeutic applications.
Purpose of the Study:
- To investigate the effect of histidine on beta-adrenoceptor desensitization.
- To determine if histidine influences epinephrine-induced suppression of uterine contractions.
Main Methods:
- Experiments utilized 62 longitudinal uterine horn strips from 10 nonpregnant rats.
- Continuous infusion of high-concentration epinephrine (10^-6 g/ml) was used to induce receptor desensitization.
- Varying concentrations of histidine were tested for their effects on desensitization.
Main Results:
- High-concentration epinephrine progressively decreased its ability to suppress spontaneous contractions, indicating receptor desensitization.
- Low histidine concentration (3 x 10^-11 g/ml) had no effect.
- Higher histidine concentrations (3 x 10^-8 to 3 x 10^-6 g/ml) reduced the degree of desensitization.
Conclusions:
- Histidine potentiates beta-adrenoceptor activation.
- Histidine prevents the development of beta-adrenoceptor desensitization.
- These findings suggest histidine could be beneficial in therapies involving beta-adrenoceptor agonists.