Assessment of histamine, bradykinin, prostaglandins E1 and E2 and carrageenin as vascular permeability agents in the horse.

This research article investigates the impact of different substances such as histamine, bradykinin, serotonin, prostaglandins E1 and E2, and carrageenin on vascular leakage in horses.

Research Methods

• The study involved intradermal injections of the substances into horses’ thoracic skin, and observation of the subsequent vascular leakage.
• The extent of leakage was assessed in two ways: first, by recording the diameter of resulting lesions in a semi-quantitative method, and second, by measuring the volume of leaked plasma using iodine-125-labelled human serum albumin (125I-HSA) as a marker in the blood plasma.
• Another part of the study involved investigating the vascular leakage induced by carrageenin, as well as the impact of prostaglandins E1 and E2 when co-administered with histamine and bradykinin.

Results and Findings

• Although serotonin injections did not result in any apparent lesions, histamine and bradykinin induced circular lesions that expanded for around 30 minutes.
• The size of lesions and the volume of leaked plasma was found to be dependent on the dosage of the injected substance. Bradykinin was more potent than histamine except at the dosage of 10(-4) mol/l, where they had the same potency.
• Lesions resulting from carrageenin injections were independent of their anatomical location on the thoracic area.
• Hourly vascular leakage volume increased till the fifth hour of observation, except for the second hour.
• The maximum vascular leakage from prostaglandin E1 or E2 was observed to be 7 microliters, however when co-administered with bradykinin, the leaked plasma volume increased significantly from 29 to 78 microliters.
• There was no observed synergy or amplified effect when either prostaglandin was co-administered with histamine.

Conclusions

• These findings provide important insights into the vascular response in horses to different substances and molecular compounds. This could be useful in improving understanding of and treatments for conditions related to vascular leakage in horses.