Tags

Type your tag names separated by a space and hit enter

Studies on endothelin release and Na,K transport in porcine lens.
Invest Ophthalmol Vis Sci. 2002 Mar; 43(3):790-6.IO

Abstract

PURPOSE

In an earlier study it was reported that thrombin significantly reduces the rate of Na,K-adenosine triphosphatase (ATPase)-mediated ion transport by porcine lens. Because thrombin stimulates the release of endogenous endothelin (ET)-1 stores from some tissues, and because ET-1 can cause Na,K-ATPase inhibition, this study was designed to determine whether thrombin causes release of ET-1 from the lens.

METHODS

Intact porcine lenses were incubated in Krebs solution. The concentration of ET-1 in the solution was determined by ELISA. The rate of Na,K-ATPase-dependent ion transport was determined by measurement of ouabain-sensitive (86)Rb uptake.

RESULTS

Thrombin (1 U/mL) reduced the rate of ouabain-sensitive (86)Rb uptake by approximately 40%. PD145065 (2 microM), an ET receptor antagonist, abolished the inhibitory effect of thrombin on (86)Rb uptake. Added alone, PD145065 did not alter (86)Rb uptake. After an incubation period of 30 minutes, thrombin increased the concentration of ET-1 in the bathing medium in a dose-dependent manner. The time course of ET-1 appearance in the bathing medium of thrombin-treated lenses showed a peak at 30 minutes followed by a gradual decline. Consistent with the idea that release of ET-1 from the lens is tightly regulated, neither the calcium ionophore A23187 (1 microM) nor depolarization by potassium-rich solution caused significant release. However, exposing the lens to insulin (150 nM) significantly increased the appearance of ET-1 in the bathing medium. In parallel studies, mRNA for prepro-ET-1 was detected in the epithelium of freshly isolated lenses.

CONCLUSIONS

The results of the study suggest that ET-1 is produced in porcine lens cells and that thrombin and insulin are capable of stimulating the release of ET-1 from the lens. Thrombin-induced inhibition of Na,K-ATPase-dependent ion transport may be mediated in part through the activation of ET-1 receptors by ET-1 released from the lens.

Authors+Show Affiliations

Department of Ophthalmology and Visual Sciences, University of Louisville School of Medicine, 301 E. Muhammad Ali Boulevard, Louisville, KY 40202, USA.No affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Research Support, Non-U.S. Gov't
Research Support, U.S. Gov't, P.H.S.

Language

eng

PubMed ID

11867600

Citation

Okafor, Mansim C., et al. "Studies On Endothelin Release and Na,K Transport in Porcine Lens." Investigative Ophthalmology & Visual Science, vol. 43, no. 3, 2002, pp. 790-6.
Okafor MC, Mukhopadhyay P, Delamere NA. Studies on endothelin release and Na,K transport in porcine lens. Invest Ophthalmol Vis Sci. 2002;43(3):790-6.
Okafor, M. C., Mukhopadhyay, P., & Delamere, N. A. (2002). Studies on endothelin release and Na,K transport in porcine lens. Investigative Ophthalmology & Visual Science, 43(3), 790-6.
Okafor MC, Mukhopadhyay P, Delamere NA. Studies On Endothelin Release and Na,K Transport in Porcine Lens. Invest Ophthalmol Vis Sci. 2002;43(3):790-6. PubMed PMID: 11867600.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Studies on endothelin release and Na,K transport in porcine lens. AU - Okafor,Mansim C, AU - Mukhopadhyay,Partha, AU - Delamere,Nicholas A, PY - 2002/2/28/pubmed PY - 2002/3/29/medline PY - 2002/2/28/entrez SP - 790 EP - 6 JF - Investigative ophthalmology & visual science JO - Invest Ophthalmol Vis Sci VL - 43 IS - 3 N2 - PURPOSE: In an earlier study it was reported that thrombin significantly reduces the rate of Na,K-adenosine triphosphatase (ATPase)-mediated ion transport by porcine lens. Because thrombin stimulates the release of endogenous endothelin (ET)-1 stores from some tissues, and because ET-1 can cause Na,K-ATPase inhibition, this study was designed to determine whether thrombin causes release of ET-1 from the lens. METHODS: Intact porcine lenses were incubated in Krebs solution. The concentration of ET-1 in the solution was determined by ELISA. The rate of Na,K-ATPase-dependent ion transport was determined by measurement of ouabain-sensitive (86)Rb uptake. RESULTS: Thrombin (1 U/mL) reduced the rate of ouabain-sensitive (86)Rb uptake by approximately 40%. PD145065 (2 microM), an ET receptor antagonist, abolished the inhibitory effect of thrombin on (86)Rb uptake. Added alone, PD145065 did not alter (86)Rb uptake. After an incubation period of 30 minutes, thrombin increased the concentration of ET-1 in the bathing medium in a dose-dependent manner. The time course of ET-1 appearance in the bathing medium of thrombin-treated lenses showed a peak at 30 minutes followed by a gradual decline. Consistent with the idea that release of ET-1 from the lens is tightly regulated, neither the calcium ionophore A23187 (1 microM) nor depolarization by potassium-rich solution caused significant release. However, exposing the lens to insulin (150 nM) significantly increased the appearance of ET-1 in the bathing medium. In parallel studies, mRNA for prepro-ET-1 was detected in the epithelium of freshly isolated lenses. CONCLUSIONS: The results of the study suggest that ET-1 is produced in porcine lens cells and that thrombin and insulin are capable of stimulating the release of ET-1 from the lens. Thrombin-induced inhibition of Na,K-ATPase-dependent ion transport may be mediated in part through the activation of ET-1 receptors by ET-1 released from the lens. SN - 0146-0404 UR - https://www.unboundmedicine.com/medline/citation/11867600/Studies_on_endothelin_release_and_NaK_transport_in_porcine_lens_ L2 - https://iovs.arvojournals.org/article.aspx?volume=43&issue=3&page=790 DB - PRIME DP - Unbound Medicine ER -