Evaluation of activation of protein kinase C during agonist-induced constriction of veins isolated from the laminar dermis of horses.

The research investigates the effects of a protein kinase C (PKC) inhibitor on the contraction of veins and arteries isolated from the skin layer of horses, as induced by certain bioactive substances. The study found that PKC activation is specific to vein contraction.

Methodology

• The study used laminar arteries and veins harvested from 8 adult mixed-breed horses.
• These isolated blood vessels were then mounted on a device known as small vessel myographs which measure the isometric tension – the tension produced by a muscle (or in this case, blood vessels) without change in its length.
• Concentration-response curves were obtained for four vasoconstrictor agonists: phenylephrine, 5-hydroxytryptamine, prostaglandin F(2), and endothelin-1. Vasoconstrictor agonists are agents that cause blood vessel constriction or contraction, resulting in decreased vessel diameter.
• The responses were measured both with and without the addition of the PKC inhibitor Ro-31-8220 at a concentration of 3 microM.

Results and Conclusion

• The results showed that laminar veins were more responsive to the vasoconstrictor agonists than the laminar arteries.
• Incubation of the veins with the PKC inhibitor resulted in notably smaller contractile responses for all vasoconstrictors tested.
• However, the PKC inhibitor did not affect the contractive responses in the laminar arteries.
• This led to the conclusion that the activation of PKC is specific to the agonist-induced contraction of the veins isolated from the skin layer of horses.
• The findings suggest that PKC could possibly play a role in the venoconstriction, or narrowing of veins, observed during the development of laminitis, a painful disease condition in horses affecting the hooves.
• The researchers suggest that this possible involvement of PKC in vein constriction during the course of laminitis is worthy of further investigation.