Lyn- and ERK-mediated vs. Ca super(2+)-mediated neutrophil O sub(2) super(-) responses with thermal injury

• Published in: American Journal of Physiology: Cell Physiology 2002-11, Vol.283 (5), p.C1469-C1479
• Main Authors: Fazal, N, Al-Ghoul, WM, Schmidt, MJ, Choudhry, MA, Sayeed, M M
• Format: Article
• Language: English
• ISSN: 0363-6143
• DOI: 10.1152/ajpcell.00114.2002

We evaluated the dependency of neutrophil O sub(2) super(-) production on PTK-Lyn and MAPK-ERK1/2 in rats after thermal injury. Activation of PTK-Lyn was assessed by immunoprecipitation. Phosphorylation of ERK1/2 was assessed by Western blot analysis. O sub(2) super(-) production was measured by isoluminol-enhanced luminometry. Imaging technique was employed to measure neutrophil [Ca super(2+)] sub(i) in individual cells. Thermal injury caused marked upregulation of Lyn and ERK1/2 accompanying enhanced neutrophil O sub(2) super(-) production. Treatment of rats with PTK blocker (AG556) or MAPK blocker (AG1478) before burn injury caused complete inhibition of the respective kinase activation. Both AG556 and AG1478 produced an similar to 66% inhibition in O sub(2) super(-) production. Treatment with diltiazem (DZ) produced an similar to 37% inhibition of O sub(2) super(-) production without affecting Lyn or ERK1/2 activation with burn injury. Ca super(2+) mobilization was upregulated with burn injury but not affected by treatment of burn rats with AG556. Unlike the partial inhibition of burn-induced O sub(2) super(-) production by AG556, AG1478, or DZ, platelet-activating factor antagonist (PAFa) treatment of burn rats produced near complete inhibition of O sub(2) super(-) production. PAFa treatment also blocked activation of Lyn. The findings suggest that the near complete inhibition of O sub(2) super(-) production by PAFa was a result of blockade of PTK as well as Ca super(2+) signaling. Overall, our studies show that enhanced neutrophil O sub(2) super(-) production after thermal injury is a result of potentiation of Ca super(2+)-linked and -independent signaling triggered by inflammatory agents such as PAF.