Purinergic agonists stimulate lens Na-K-ATPase-mediated transport via a Src tyrosine kinase-dependent pathway.

The Na-K-ATPase is vital for maintenance of lens transparency. Past studies using intact lens suggested the involvement of tyrosine kinases in short-term regulation of Na-K-ATPase. Furthermore, in vitro phosphorylation of a lens epithelial membrane preparation by Src family kinases (SFKs), a family of nonreceptor tyrosine kinases, resulted in modification of Na-K-ATPase activity.

Sodium-calcium exchange influences the response to endothelin-1 in lens epithelium.

Studies were conducted to examine the possible involvement of Na+-Ca2+ exchanger in determining the magnitude of the endothelin-1 (ET-1)-receptor-mediated calcium signal in porcine lens epithelial cells. Cytoplasmic calcium concentration was measured in primary cultured cells loaded with Fura-2. ET-1 (100 nM) caused cytoplasmic calcium to increase transiently to approximately 250 nM from a baseline of approximately 65 nM.

Studies on endothelin release and Na,K transport in porcine lens.

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.