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Threshold phenomena and interactions between receptors
1Department of Physiology and Biophysics, Mayo Clinic, Rochester, Minnesota 55905.
Journal of Cardiovascular Pharmacology
|January 1, 1988
Summary
Serotonin can amplify blood vessel contractions by removing a response threshold. Variability in this effect may stem from changes in the threshold or vasoconstrictor efficacy.
Area of Science:
- Pharmacology
- Physiology
- Vascular Biology
Background:
- Serotonin (5-HT) is known to modulate vascular tone.
- Subthreshold concentrations of serotonin can enhance responses to other vasoconstrictors.
- The precise mechanism of this facilitatory effect requires further elucidation.
Purpose of the Study:
- To theoretically analyze the phenomenon of threshold facilitation by serotonin.
- To investigate how serotonin's amplifying effect on vasoconstriction might occur.
- To explain the observed variability in serotonin's facilitatory effects.
Main Methods:
- Theoretical analysis of vascular smooth muscle response mechanisms.
- Modeling of response thresholds and agonist efficacy.
- Examination of factors influencing serotonin's interaction with vasoconstrictors.
Main Results:
- The study proposes that serotonin amplifies vasoconstrictor responses by eliminating a response threshold.
- This removal of a threshold is identified as the key mechanism for facilitation.
- Variability in serotonin's effect is linked to alterations in threshold magnitude or agonist efficacy.
Conclusions:
- Serotonin's facilitatory effect on vasoconstriction is likely mediated by the removal of a response threshold.
- Differences in this threshold or vasoconstrictor potency explain variations in serotonin's in vivo and in vitro effects.
- Understanding this mechanism is crucial for interpreting vascular responses in different physiological and pathological states.