Evaluation of activation of protein kinase C during agonist-induced constriction of veins isolated from the laminar dermis of horses.
OBJECTIVE
To determine the effects of the protein kinase C (PKC) inhibitor, Ro-31-8220, on agonist-induced constriction of laminar arteries and veins obtained from horses.


METHODS
Laminar arteries and veins obtained from 8 adult mixed-breed horses.


METHODS
Laminar arteries and veins were isolated and mounted on small vessel myographs for the measurement of isometric tension. Concentration-response curves were then obtained for the vasoconstrictor agonists phenylephrine, 5-hydroxytryptamine, prostaglandin F(2), and endothelin-1. All responses were measured with or without the addition of Ro-31-8220 (3 microM).


RESULTS
Laminar veins were more sensitive to vasoconstrictor agonists than laminar arteries, and incubation of laminar veins with Ro-31-8220 resulted in significantly smaller agonist-induced contractile responses for all agonists tested. In contrast, Ro-31-8220 had no effect on agonist-induced contractile responses of laminar arteries.


CONCLUSIONS
Results of the study were consistent with activation of PKC being confined to agonist-induced contraction of laminar veins isolated from the laminar dermis of horses. Consequently, the possible involvement of PKC in the venoconstriction observed during the development of laminitis is worthy of further investigation.
Robertson
Tom P
TP
Department of Physiology and Pharmacology, Institute of Comparative Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389, USA.
Moore
James N
JN
Noschka
Erik
E
Lewis
Tristan H
TH
Lewis
Stephen J
SJ
Peroni
John F
JF
D000818:Animals; D020405:Dermis / Q000098:blood supply*; D004789:Enzyme Activation / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006736:Horses; D007211:Indoles / Q000494:pharmacology*; D011493:Protein Kinase C / Q000378:metabolism*; D014661:Vasoconstriction / Q000187:drug effects*; D014680:Veins / Q000187:drug effects* / Q000502:physiology
D004791:Enzyme Inhibitors; D007211:Indoles; D011493:Protein Kinase C; C064758:Ro 31-8220