Abstract
► ATP release by erythrocytes is attenuated in cells of Pannexin1 deficient mice. ► The Panx1−/− cells reveal a second Panx1 independent pathway for ATP release. ► The alternate pathway is activated by iloprost and inhibited by dipyridamole. ► The alternate release mechanism does not allow for the uptake of extracellular dyes. ► Glibenclamide inhibits Panx1 in the same concentration range as it inhibits CFTR channels.
Erythrocytes are exceptionally suited for analysis of non-exocytotic release mechanisms of ATP, because these cells under physiological conditions lack vesicles. Previous studies have indicated, that Pannexin1 (Panx1) provides a key ATP permeation pathway in many cell types, including human and frog erythrocytes. Here we show that erythrocytes of Panx1−/− mice lend further support to this conclusion. However, ATP release, although attenuated, was still observed in Panx1−/− mouse erythrocytes. In contrast to Panx1+/+ cells, this release was not correlated with uptake of extracellularly applied dyes, was insensitive to Panx1 channel blockers, and was inhibited by dipyridamole and stimulated by iloprost. Thus, in erythrocytes, two independent pathways mediate the release of ATP. We also show that glyburide is a strong inhibitor of Panx1 channels.
