• 1

    Sloet van Oldruitenborgh-Oosterbaan MM. Laminitis in the horse: a review. Vet Q 1999;21:121127.

  • 2

    Adair HS III, Goble DO, Schmidhammer JL, et al. Laminar microvascular flow, measured by means of laser Doppler flowmetry, during the prodromal stages of black walnut-induced laminitis in horses. Am J Vet Res 2000;61:862868.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 3

    Galey FD, Twardock AR, Goetz TE, et al. Gamma scintigraphic analysis of the distribution of perfusion of blood in the equine foot during black walnut (Juglans nigra)-induced laminitis. Am J Vet Res 1990;51:688695.

    • Search Google Scholar
    • Export Citation
  • 4

    Allen D Jr, Clark ES, Moore JN, et al. Evaluation of equine digital Starling forces and hemodynamics during early laminitis. Am J Vet Res 1990;51:19301934.

    • Search Google Scholar
    • Export Citation
  • 5

    Eaton SA, Allen D, Eades SC, et al. Digital Starling forces and hemodynamics during early laminitis induced by an aqueous extract of black walnut (Juglans nigra) in horses. Am J Vet Res 1995;56:13381344.

    • Search Google Scholar
    • Export Citation
  • 6

    Hurley DJ, Parks RJ, Reber AJ, et al. Dynamic changes in circulating leukocytes during the induction of equine laminitis with black walnut extract. Vet Immunol Immunopathol 2006;110:195206.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 7

    Eades SC, Stokes AM, Moore RM. Effects of an endothelin receptor antagonist and nitroglycerin on digital vascular function in horses during the prodromal stages of carbohydrate overload-induced laminitis. Am J Vet Res 2006;67:12041211.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 8

    Waguespack RW, Cochran A, Belknap JK. Expression of the cyclooxygenase isoforms in the prodromal stage of black walnut-induced laminitis in horses. Am J Vet Res 2004;65:17241729.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 9

    Robertson TP, Peroni JF, Lewis SJ, et al. Effects of induction of capacitative calcium entry on equine laminar microvessels. Am J Vet Res 2005;66:18771880.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 10

    Peroni JF, Harrison WE, Moore JN, et al. Black walnut extract-induced laminitis in horses is associated with heterogeneous dysfunction of the laminar microvasculature. Equine Vet J 2005;37:546551.

    • Search Google Scholar
    • Export Citation
  • 11

    Peroni JF, Moore JN, Noschka E, et al. Predisposition for venoconstriction in the equine laminar dermis: implications in equine laminitis. J Appl Physiol 2006;100:759763.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 12

    Somlyo AP, Somlyo AV. Signal transduction by G-proteins, rhokinase and protein phosphatase to smooth muscle and non-muscle myosin II. J Physiol 2000;522:177185.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 13

    Somlyo AP, Somlyo AV. Signal transduction and regulation in smooth muscle. Nature 1994;372:231236.

  • 14

    DeFeo TT, Morgan KG. Calcium-force relationships as detected with aequorin in two different vascular smooth muscles of the ferret. J Physiol 1985;369:269282.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 15

    Morgan JP, Morgan KG. Stimulus-specific patterns of intracellular calcium levels in smooth muscle of ferret portal vein. J Physiol 1984;351:155167.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 16

    Nishimura J, Khalil RA, vanBreemen C. Agonist-induced vascular tone. Hypertension 1989;13:835844.

  • 17

    Steusloff A, Paul E, Semenchuk LA, et al. Modulation of Ca2+ sensitivity in smooth muscle by genistein and protein tyrosine phosphorylation. Arch Biochem Biophys 1995;320:236242.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 18

    Nagao M, Kaziro Y, Itoh H. The Src family tyrosine kinase is involved in Rho-dependent activation of c-Jun N-terminal kinase by Galpha12. Oncogene 1999;18:44254434.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 19

    Nakao F, Kobayashi S, Mogami K, et al. Involvement of Src family protein tyrosine kinases in Ca2+ sensitization of coronary artery contraction mediated by a sphingosylphosphorylcholine-Rho-kinase pathway. Circ Res 2002;91:953960.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 20

    Sasaki M, Hattori Y, Tomita F, et al. Tyrosine phosphorylation as a convergent pathway of heterotrimeric G protein- and Rho protein-mediated Ca2+ sensitization of smooth muscle of rabbit mesenteric artery. Br J Pharmacol 1998;125:16511660.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 21

    2000 Report of the AVMA Panel on Euthanasia. J Am Vet Med Assoc 2001;218:669696.

  • 22

    Winer BJ. Analysis of variance. In:Statistics principles in experimental design. New York: McGraw-Hill, 1971;752809.

  • 23

    Wallenstein S, Zucker CL, Fleiss JL. Some statistical methods useful in circulation research. Circ Res 1980;47:19.

  • 24

    Hanke JH, Gardner JP, Dow RL, et al. Discovery of a novel, potent, and Src family-selective tyrosine kinase inhibitor. Study of Lck- and FynT-dependent T cell activation. J Biol Chem 1996;271:695701.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 25

    Hood DM. The pathophysiology of developmental and acute laminitis. Vet Clin North Am Equine Pract 1999;15:321343.

  • 26

    Hood DM, Grosenbaugh DA, Mostafa MB, et al. The role of vascular mechanisms in the development of acute equine laminitis. J Vet Intern Med 1993;7:228234.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 27

    Moore RM, Eades SC, Stokes AM. Evidence for vascular and enzymatic events in the pathophysiology of acute laminitis: which pathway is responsible for initiation of this process in horses? Equine Vet J 2004;36:204209.

    • Search Google Scholar
    • Export Citation
  • 28

    Tamura M, Nakao H, Yoshizaki H, et al. Development of specific Rho-kinase inhibitors and their clinical application. Biochim Biophys Acta 2005;1754:245252.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 29

    Shimokawa H, Takeshita A. Rho-kinase is an important therapeutic target in cardiovascular medicine. Arterioscler Thromb Vasc Biol 2005;25:17671775.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 30

    Lee MW, Severson DL. Signal transduction in vascular smooth muscle: diacylglycerol second messengers and PKC action. Am J Physiol 1994;267:C659C678.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 31

    Di Salvo J, Pfitzer G, Semenchuk LA. Protein tyrosine phosphorylation, cellular Ca2+, and Ca2+ sensitivity for contraction of smooth muscle. Can J Physiol Pharmacol 1994;72:14341439.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 32

    Uehata M, Ishizaki T, Satoh H, et al. Calcium sensitization of smooth muscle mediated by a Rho-associated protein kinase in hypertension. Nature 1997;389:990994.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 33

    Davies SP, Reddy H, Caivano M, et al. Specificity and mechanism of action of some commonly used protein kinase inhibitors. Biochem J 2000;351:95105.

  • 34

    Robertson TP, Michelakis ED, Rochefort GY. Release of an endothelium-derived vasoconstrictor and RhoA/Rho kinase mediated calcium sensitization of smooth muscle cell contraction are/ are not the main effectors for full and sustained hypoxic pulmonary vasoconstriction. J Appl Physiol 2007;102:20712072.

    • Crossref
    • Search Google Scholar
    • Export Citation
  • 35

    Evans AM, Cobban HJ, Nixon GF. ET(A) receptors are the primary mediators of myofilament calcium sensitization induced by ET-1 in rat pulmonary artery smooth muscle: a tyrosine kinase independent pathway. Br J Pharmacol 1999;127:153160.

    • Crossref
    • Search Google Scholar
    • Export Citation

Advertisement

Effects of Rho-kinase and Src protein tyrosine kinase inhibition on agonist-induced vasoconstriction of arteries and veins of the equine laminar dermis

Tom P. RobertsonDepartment of Physiology and Pharmacology, Institute of Comparative Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.

Search for other papers by Tom P. Robertson in
Current site
Google Scholar
PubMed
Close
 PhD
,
James N. MooreDepartment of Physiology and Pharmacology, Institute of Comparative Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.

Search for other papers by James N. Moore in
Current site
Google Scholar
PubMed
Close
 DVM, PhD
,
Erik NoschkaDepartment of Physiology and Pharmacology, Institute of Comparative Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.

Search for other papers by Erik Noschka in
Current site
Google Scholar
PubMed
Close
 DVM
,
Tristan H. LewisDepartment of Physiology and Pharmacology, Institute of Comparative Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.

Search for other papers by Tristan H. Lewis in
Current site
Google Scholar
PubMed
Close
 PhD
,
Stephen J. LewisDepartment of Physiology and Pharmacology, Institute of Comparative Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.

Search for other papers by Stephen J. Lewis in
Current site
Google Scholar
PubMed
Close
 PhD
, and
John F. PeroniDepartment of Physiology and Pharmacology, Institute of Comparative Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.
Department of Large Animal Medicine, College of Veterinary Medicine, University of Georgia, Athens, GA 30602-7389.

Search for other papers by John F. Peroni in
Current site
Google Scholar
PubMed
Close
 DVM, MS

Abstract

Objective—To determine the effects of inhibition of Rho-kinase or Src-family protein tyrosine kinases (srcPTK) on agonist-induced contractile responses in equine laminar arteries and veins.

Sample Population—Laminar arteries and veins obtained from 13 adult mixed-breed horses.

Procedures—Laminar vessels were mounted on myographs and exposed to phenylephrine (PE), 5-hydroxytryptamine (5-HT), prostaglandin F (PGF), and endothelin-1 (ET-1) with or without the Rho-kinase inhibitor Y-27632 (10μM), srcPTK inhibitor PP2 (10μM), or a negative control analogue for PP2 (PP3; 10μM).

Results—Responses to PE were reduced by use of Y-27632 in laminar vessels (approx inhibition, 55%). However, Y-27632 reduced responses to 5-HT to a greater degree in veins than in arteries (approx inhibition of 55% and 35%, respectively). The Y-27632 also reduced responses of laminar veins to ET-1 by approximately 40% but had no effect on maximum responses of laminar arteries to ET-1, although a rightward shift in the concentration response curve was evident. Addition of PP2 reduced responses to PE, 5-HT, and PGF in laminar veins by approximately 40%, 60%, and 65%, respectively, compared with responses after the addition of PP3; PP2 had no effect on responses to ET-1. In laminar arteries, PP2 reduced 5-HT–induced contractions by approximately 50% but did not affect responses to PE or ET-1.

Conclusions and Clinical Relevance—Results of the study were consistent with activation of Rho-kinase being important during agonist-induced constriction in laminar vessels, activation of srcPTK being an agonist-dependent event, and more prominent roles for Rhokinase and srcPTK in veins than in arteries.

Abstract

Objective—To determine the effects of inhibition of Rho-kinase or Src-family protein tyrosine kinases (srcPTK) on agonist-induced contractile responses in equine laminar arteries and veins.

Sample Population—Laminar arteries and veins obtained from 13 adult mixed-breed horses.

Procedures—Laminar vessels were mounted on myographs and exposed to phenylephrine (PE), 5-hydroxytryptamine (5-HT), prostaglandin F (PGF), and endothelin-1 (ET-1) with or without the Rho-kinase inhibitor Y-27632 (10μM), srcPTK inhibitor PP2 (10μM), or a negative control analogue for PP2 (PP3; 10μM).

Results—Responses to PE were reduced by use of Y-27632 in laminar vessels (approx inhibition, 55%). However, Y-27632 reduced responses to 5-HT to a greater degree in veins than in arteries (approx inhibition of 55% and 35%, respectively). The Y-27632 also reduced responses of laminar veins to ET-1 by approximately 40% but had no effect on maximum responses of laminar arteries to ET-1, although a rightward shift in the concentration response curve was evident. Addition of PP2 reduced responses to PE, 5-HT, and PGF in laminar veins by approximately 40%, 60%, and 65%, respectively, compared with responses after the addition of PP3; PP2 had no effect on responses to ET-1. In laminar arteries, PP2 reduced 5-HT–induced contractions by approximately 50% but did not affect responses to PE or ET-1.

Conclusions and Clinical Relevance—Results of the study were consistent with activation of Rho-kinase being important during agonist-induced constriction in laminar vessels, activation of srcPTK being an agonist-dependent event, and more prominent roles for Rhokinase and srcPTK in veins than in arteries.

Contributor Notes

Supported by the National Research Initiative of the USDA Cooperative State Research, Education and Extension Service (grants No. 2003-35204-13350 and 2002-35204-12423); Morris Animal Foundation; White Fox Farm Research Fund; and Pfizer Animal Health.

The authors thank Megan E. Grafton and Maria Aceves-Avila for technical assistance.

Address correspondence to Dr. Robertson.