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Histamine receptors in the cat mesenteric circulation.
Experientia
|January 15, 1976
Summary
Histamine receptors in cat ileum were studied. Histamine causes blood vessel dilation via H2-receptors and constriction via H1-receptors.
Area of Science:
- Pharmacology
- Physiology
- Vascular Biology
Background:
- Histamine receptors play a crucial role in regulating vascular tone.
- Understanding receptor subtypes involved in histamine's vascular effects is essential for therapeutic development.
Purpose of the Study:
- To investigate the specific histamine receptor subtypes mediating vascular responses in the cat terminal ileum.
- To differentiate the roles of H1 and H2 receptors in histamine-induced vasodilation and vasoconstriction.
Main Methods:
- Utilized an isolated perfused vascular bed model of the cat terminal ileum.
- Administered histamine and receptor-specific antagonists (metiamide for H2, mepyramine for H1).
- Monitored changes in vascular pressure to assess depressor and pressor effects.
Main Results:
- Histamine induced a depressor effect (vasodilation) mediated by metiamide-sensitive H2-receptors.
- Histamine induced a pressor effect (vasoconstriction) mediated by mepyramine-sensitive H1-receptors.
Conclusions:
- The cat terminal ileum's vascular bed exhibits distinct H1 and H2 histamine receptor populations.
- H2-receptors mediate histamine-induced vasodilation, while H1-receptors mediate vasoconstriction in this vascular bed.