Research

Intracellular calcium changes induced by the endozepine triakontatetraneuropeptide in human polymorphonuclear leukocytes: role of protein kinase C and effect of calcium channel blockers

Franca Marino¹ , Marco Cosentino¹ , Marco Ferrari¹ , Simona Cattaneo¹ , Giuseppina Frigo¹ , Anna M Fietta² , Sergio Lecchini¹ and Gian Mario Frigo³

¹  Department of Clinical Medicine, Section of Experimental and Clinical Pharmacology, University of Insubria, Varese, Italy

²  Department of Hematological, Pneumological and Cardiovascular Sciences, University of Pavia, Pavia, Italy

³  Department of Internal Medicine and Therapeutics, Section of Pharmacology and Toxicology, University of Pavia, Pavia, Italy

author email corresponding author email

Cell Communication and Signaling 2004, 2:6doi:10.1186/1478-811X-2-6

Published:	30 June 2004

Abstract

Background

The endozepine triakontatetraneuropeptide (TTN) induces intracellular calcium ([Ca⁺⁺]_i) changes followed by activation in human polymorphonuclear leukocytes (PMNs). The present study was undertaken to investigate the role of protein kinase (PK) C in the modulation of the response to TTN by human PMNs, and to examine the pharmacology of TTN-induced Ca⁺⁺ entry through the plasma membrane of these cells.

Results

The PKC activator 12-O-tetradecanoylphorbol-13-acetate (PMA) concentration-dependently inhibited TTN-induced [Ca⁺⁺]_i rise, and this effect was reverted by the PKC inhibitors rottlerin (partially) and Ro 32-0432 (completely). PMA also inhibited TTN-induced IL-8 mRNA expression. In the absence of PMA, however, rottlerin (but not Ro 32-0432) per se partially inhibited TTN-induced [Ca⁺⁺]_i rise. The response of [Ca⁺⁺]_i to TTN was also sensitive to mibefradil and flunarizine (T-type Ca⁺⁺-channel blockers), but not to nifedipine, verapamil (L-type) or ω-conotoxin GVIA (N-type). In agreement with this observation, PCR analysis showed the expression in human PMNs of the mRNA for all the α1 subunits of T-type Ca⁺⁺ channels (namely, α1G, α1H, and α1I).

Conclusions

In human PMNs TTN activates PKC-modulated pathways leading to Ca⁺⁺ entry possibly through T-type Ca⁺⁺ channels.