Inhibition of extracellular Ca(2+) entry by YC-1, an activator of soluble guanylyl cyclase, through a cyclic GMP-independent pathway in rat neutrophils.
The effects of a soluble guanylyl cyclase (sGC) activator, 3-(5'-hydroxymethyl-2'-furyl)-1-benzyl indazole (YC-1), on formyl-methionyl-leucyl-phenylalanine (fMLP)-stimulated [Ca(2+)](i) elevation in rat neutrophils were examined. YC-1 produced a concentration-dependent inhibition of [Ca(2+)](i) elevation. Pretreatment of neutrophils with YC-1 did not enhance its inhibitory effect. YC-1 also inhibited the [Ca(2+)](i) changes caused by ionomycin. In a biphasic model, measuring the [Ca(2+)](i) stimulation by fMLP in a Ca(2+)-free medium followed by reintroduction of Ca(2+), YC-1 mainly affected Ca(2+) influx. YC-1 also inhibited active and passive Mn(2+) influx, and this inhibitory effect was not attenuated by the sGC inhibitor 6-anilino-5,8-quinolinequinone (LY83583). Sodium nitroprusside did not affect the fMLP-stimulated [Ca(2+)](i) changes. Pretreatment of neutrophils with the cyclic GMP-dependent protein kinase inhibitor 8-(4-chlorophenylthio) guanosine-3',5'-monophosphorothioate, Rp-isomer (Rp-8-pCPT-cGMPS), LY83583, the protein phosphatase 2B inhibitor cyclosporin A, or the protein kinase inhibitor staurosporine did not attenuate the inhibition of [Ca(2+)](i) by YC-1. YC-1 inhibited the fMLP-stimulated protein tyrosine phosphorylation. These results indicate that cyclic GMP does not play an important role in the regulation of [Ca(2+)](i) in rat neutrophils. Inhibition of fMLP-stimulated [Ca(2+)](i) changes by YC-1 is mainly via the blockade of Ca(2+) entry through the inhibition of tyrosine kinase activity, but not the stimulation of protein kinase C and protein phosphatase 2B.
Wang
J P
JP
Department of Education and Research, Taichung Veterans General Hospital, 407, ROC, Taichung, Taiwan. w1994@vghtc.gov.tw
Chang
L C
LC
Huang
L J
LJ
Kuo
S C
SC
D000818:Animals; D002118:Calcium / Q000378:metabolism*; D006152:Cyclic GMP / Q000378:metabolism*; D004789:Enzyme Activation; D006162:Guanylate Cyclase / Q000378:metabolism*; D066298:In Vitro Techniques; D007191:Indazoles / Q000494:pharmacology*; D017136:Ion Transport; D008345:Manganese / Q000378:metabolism; D009504:Neutrophils / Q000187:drug effects* / Q000201:enzymology / Q000378:metabolism; D010766:Phosphorylation; D010975:Platelet Aggregation Inhibitors / Q000494:pharmacology*; D051381:Rats; D012995:Solubility; D014443:Tyrosine / Q000378:metabolism
D007191:Indazoles; D010975:Platelet Aggregation Inhibitors; C090937:3-(5'-hydroxymethyl-2'-furyl)-1-benzylindazole; D014443:Tyrosine; D008345:Manganese; D006162:Guanylate Cyclase; D006152:Cyclic GMP; D002118:Calcium