Characteristics of myogenic tone in the rat ophthalmic artery

Isamu Ito, Yagna P R Jarajapu, Maria B. Grant, Harm J. Knot

Research output: Contribution to journalArticle

11 Citations (Scopus)

Abstract

The pressure-induced constriction in the rat ophthalmic artery was characterized. Ophthalmic arteries were isolated, cannulated in an arteriograph, and pressurized. Arteries developed 25% constriction at 70 mmHg of intraluminal pressure. Arteries maintained almost similar diameter over the range of pressures 50-210 mmHg, and forced dilatation was observed at pressures >210 mmHg. Denudation of endothelium increased the sensitivity of arteries to pressure-induced constriction, and significantly higher myogenic tone was observed in the pressure range of 10-100 mmHg. Indomethacin and cyclooxygenase-2 inhibition by SC-236 decreased myogenic tone, whereas cyclooxygenase-1 inhibition by SC-560 potentiated myogenic tone in a lower concentration range and decreased at a higher concentration. Pressure-induced constriction was completely blocked by 1 μM nifedipine. Phospholipase C inhibition by 6 μM U-73122 decreased myogenic tone by 39%, whereas PKC inhibitor GF-109203X (3 μM) had no effect. Constriction to phenylephrine was significantly decreased by U-73122 (1 μM) and GF-109203X (3 μM) at an intraluminal pressure of 10 mmHg. Rho-kinase inhibition by Y-27632 (30 μM) and HA-1077 (30 μM) decreased myogenic tone by 75% and 73%, respectively, and 1 μM Y-27632 significantly decreased myogenic tone developed in response to graded increases in pressure. These results suggest that rat ophthalmic artery has an efficient pressure-dependent autoregulatory function that is modulated by endothelium. Contribution of phospholipase C-activation to myogenic tone is minimal, whereas Rho-kinase activation plays a predominant role in the myogenic reactivity in this artery.

Original languageEnglish (US)
JournalAmerican Journal of Physiology - Heart and Circulatory Physiology
Volume292
Issue number1
DOIs
StatePublished - Jan 2007
Externally publishedYes

Fingerprint

Ophthalmic Artery
Pressure
Constriction
Arteries
rho-Associated Kinases
Type C Phospholipases
Endothelium
Cyclooxygenase 1
Phenylephrine
Cyclooxygenase 2
Nifedipine
Indomethacin
Dilatation

Keywords

  • Endothelium
  • Phospholipase C
  • Rho kinase

ASJC Scopus subject areas

  • Physiology

Cite this

Characteristics of myogenic tone in the rat ophthalmic artery. / Ito, Isamu; Jarajapu, Yagna P R; Grant, Maria B.; Knot, Harm J.

In: American Journal of Physiology - Heart and Circulatory Physiology, Vol. 292, No. 1, 01.2007.

Research output: Contribution to journalArticle

Ito, Isamu ; Jarajapu, Yagna P R ; Grant, Maria B. ; Knot, Harm J. / Characteristics of myogenic tone in the rat ophthalmic artery. In: American Journal of Physiology - Heart and Circulatory Physiology. 2007 ; Vol. 292, No. 1.
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