Berts A, Minneman KP. Tyrosine kinase inhibitors and Ca2+ signaling: direct interactions with fura-2.
Eur J Pharmacol 2000;
389:35-40. [PMID:
10686293 DOI:
10.1016/s0014-2999(99)00854-7]
[Citation(s) in RCA: 10] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Selective inhibitors were used to study the role of tyrosine kinases in alpha(1A)-adrenoceptor-mediated responses in transfected PC12 cells. Ca(2+) responses to noradrenaline were measured using fura-2, and the effects of genistein, tyrphostin A25, and herbimycin A were examined. Neither genistein nor herbimycin A pretreatment altered noradrenaline-induced Ca(2+) responses, although tyrphostin A25 pretreatment caused some reduction. However, acute addition of genistein quickly reversed the apparent noradrenaline response, apparently, through a direct interaction with cytoplasmic fura-2. Both genistein and tyrphostin A25, at concentrations similar to those used to inhibit tyrosine kinases, markedly reduced fluorescence of fura-2 excited by both 340 and 380 nm, and genistein also reduced the 340/380 ratio. Tyrosine kinase inhibitors did not alter noradrenaline stimulated inositol phosphate formation in alpha(1A)-PC12 cells. These results suggest that tyrosine kinases are not involved in second messenger responses to alpha(1A)-adrenoceptors, but that tyrosine kinase inhibitors can interact directly with fura-2.
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