| RESEARCH PAPER
|Year : 1986 | Volume
| Issue : 4 | Page : 207-210
Histamine induces reflex hypotension through gut receptors in rabbits
V Radhakrishnan, KN Sharma
1. Application of 200 (g dose of histamine to the serosal surface of stomach or intestine in urethane anaesthetized rabbits produced within l-3 sec, a significant fall in blood pressure without affecting the heart rate and respiration.
2. This effect persisted even after intravenous administration of cimetidine (2 mg/kg) ruling out the possibility of a direct action of histamine on H2 receptors of vascular smooth muscles.
3. The response was effectively blocked by pretreatment of the serosa with mepyramine, but not by cimetidine. Application of 2-methyl histamine to gut serosa produced a similar fall in blood pressure as produced by histamine, and application of 4-methyl histamine did not produce any significant change.
4. The effect of serosal application of histamine was not affected by bilateral abdominal vagotomy, but was totally abolished by splanchnicotomy.
5. These results indicate that stimulation of H1- receptors of the gut leads to a reflex fall in blood pressure mediated through the splanchnic afferents. As the response is not associated with any change in heart rate, a reduction in sympathetic efferent discharge leading to vasodilation could possibly be the cause for hypotension.
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