Effect of tyrosine kinase blockade on norepinephrine-induced cytosolic calcium response in rat afferent arterioles

Abstract

We used genistein (Gen) and tyrphostin 23 (Tyr-23) to evaluate the importance of tyrosine phosphorylation in norepinephrine (NE)-induced changes in intracellular free calcium concentration ([Ca(2+)](i)) in rat afferent arterioles. [Ca(2+)](i) was measured in microdissected arterioles using ratiometric photometry of fura 2 fluorescence. The control [Ca(2+)](i) response to NE (1 microM) consisted of a rapid initial peak followed by a plateau phase sustained above baseline. Pretreatment with the tyrosine kinase inhibitor Tyr-23 (50 microM, 10 min) caused a slow 40% increase in baseline [Ca(2+)](i). Tyr-23 attenuated peak and plateau responses to NE, both by approximately 70%. In the absence of extracellular Ca(2+) (0 Ca), Tyr-23 reduced the immediate [Ca(2+)](i) response to NE by approximately 60%, indicative of mobilization of internal stores, and abolished the plateau phase. In other arterioles, the [Ca(2+)](i) response to depolarization induced by KCl (50 mM) was not attenuated by Tyr-23, indicating no direct effect on L-type Ca(+) channels activated by depolarization. The Ca(2+) channel blocker nifedipine (1 microM) inhibited the NE response by approximately 50%; the effects of nifedipine and Tyr-23 were not additive. Nifedipine had no inhibitory effect after Tyr-23 pretreatment, indicating Tyr-23 inhibition of Ca(2+) entry. Another tyrosine kinase inhibitor, Gen (5 and 50 microM), did not affect baseline [Ca(2+)](i). High-dose Gen inhibited the peak and plateau response to NE by 87 and 75%, respectively; low-dose Gen attenuated both responses by approximately 20%. In 0 Ca, Gen (50 microM) abolished the immediate [Ca(2+)](i) mobilization response. Combined nifedipine and Gen (50 microM) inhibited the rapid NE response by approximately 90% in the presence of extracellular Ca(2+). Gen (50 microM) also inhibited by 60% the [Ca(2+)](i) response to 50 mM KCl, indicating a direct interaction with voltage-sensitive, L-type Ca(2+) entry channels. These results indicate that tyrosine phosphorylation is an important link in the chain of events leading to alpha-adrenoceptor-induced Ca(2+) recruitment (both entry and release) in afferent arteriolar smooth muscle cells. Furthermore, different blockers of tyrosine kinase appear to have different modes of action in renal microvessels.

Involvement of BK α subunit tyrosine phosphorylation in vascular hyporesponsiveness of superior mesenteric artery following hemorrhagic shock in rats

“…PTK and/or PTP mediated BK Ca a subunit tyrosine phosphorylation and BK Ca activation could lead to the hyperpolarization of VSMC membrane and the close of voltage-sensitive calcium channel, which could facilitate the development of vascular hyporesponsiveness in hemorrhagic shock. Salomonsson and Arendshorst reported that genistein could inhibit the NE-induced vasoconstriction through decreasing intracellular [Ca 2+ ] and the sensitivity of contractile apparatus to Ca 2+ at higher concentration (5 Â 10 À 2 mol/L) [22], while genistein induced the restitution of the decreased vascular reactivity in the present study at much lower concentration (10 À 5 mol/L). It was suggested that genistein could have different dose-dependent effects on NE-induced vasoconstriction and vascular reactivity through different mechanisms.…”

Reduced alpha adrenergic mediated contraction of renal preglomerular blood vessels as a function of gender and aging

“…Afferent arteriolar calcium entry and release associated with afferent arteriolar constriction with angiotensin II [Che and Carmines, 2002] and norepinephrine [Salomonsson and Arendshorst, 2004] were also reduced by TyrK blockade. The L-type calcium channel blocker, nifendipine had no effect on calcium entry in the TyrK-blockertreated arterioles suggesting that TyrK plays a major role in calcium entry during norepinephrine contraction [Salomonsson and Arendshorst, 2004]. It is clear that there is an interaction between vasoconstrictor agonists and TyrK activity, particularly the TyrK of the EGF receptor.…”

“…When a TyrK inhibitor (AG1478) that specifically blocks the epidermal growth factor receptor (EGFR) TyrK was administered, the constriction to Angiotensin II in afferent and efferent arterioles was reduced 52% and 51%, respectively, suggesting that renal afferent arteriolar constriction to angiotensin II is most affected by the EGFR form of TyrK. Afferent arteriolar calcium entry and release associated with afferent arteriolar constriction with angiotensin II [Che and Carmines, 2002] and norepinephrine [Salomonsson and Arendshorst, 2004] were also reduced by TyrK blockade. The L-type calcium channel blocker, nifendipine had no effect on calcium entry in the TyrK-blockertreated arterioles suggesting that TyrK plays a major role in calcium entry during norepinephrine contraction [Salomonsson and Arendshorst, 2004].…”

Effects of Genistein on Common Kidney Diseases

“…Several studies have shown that under normal circumstances, genistein can inhibit the contraction of kidney blood vessels, including glomerular arterioles, afferent arteries, or vascular beds [140][141][142]. In addition, genistein can inhibit norepinephrine-induced vasoconstriction, but this effect is not completely dependent on extracellular Ca 2+ [143].…”