Lysophosphatidic acid-LPA1 receptor-Rho-Rho kinase-induced up-regulation of Nav1.7 sodium channel mRNA and protein in adrenal chromaffin cells: enhancement of 22Na+ influx, 45Ca2+ influx and catecholamine secretion.
In cultured bovine adrenal chromaffin cells, chronic (> or = 24 h) treatment with lysophosphatidic acid (LPA) augmented veratridine-induced 22Na+ influx via Na(v)1.7 by approximately 22% (EC(50) = 1 nmol/L), without changing nicotine-induced 22Na+ influx via nicotinic receptor-associated channel. LPA enhanced veratridine (but not nicotine)-induced 45Ca2+ influx via voltage-dependent calcium channel and catecholamine secretion. LPA shifted concentration-response curve of veratridine for 22Na+ influx upward, without altering the EC(50) of veratridine. Ptychodiscus brevis toxin-3 allosterically enhanced veratridine-induced 22Na+ influx by twofold in non-treated and LPA-treated cells. Whole-cell patch-clamp analysis showed that peak Na+ current amplitude was greater by 39% in LPA (100 nmol/L for 36 h)-treated cells; however, I-V curve and steady-state inactivation/activation curves were comparable between non-treated and LPA-treated cells. LPA treatment (> or = 24 h) increased cell surface [3H]saxitoxin binding by approximately 28%, without altering the K(d) value; the increase was prevented by cycloheximide, actinomycin D, or Ki16425, dioctylglycerol pyrophosphate 8:0 (two inhibitors of LPA(1) and LPA3 receptors), or botulinum toxin C3 (Rho inhibitor), Y27632 (Rho kinase inhibitor), consistent with LPA(1) receptor expression in adrenal chromaffin cells. LPA raised Nav1.7 mRNA level by approximately 37%. Thus, LPA-LPA(1) receptor-Rho/Rho kinase pathway up-regulated cell surface Nav1.7 and Nav1.7 mRNA levels, enhancing veratridine-induced Ca2+ influx and catecholamine secretion.
Departments of Pharmacology, and Anesthesiology, Miyazaki Medical College, University of Miyazaki, Miyazaki, Japan.
Toyoaki
T
Maruta
Toshihiko
T
Yanagita
Kiyotaka
K
Matsuo
Yasuhito
Y
Uezono
Shinya
S
Satoh
Takayuki
T
Nemoto
Norie
N
Yoshikawa
Hideyuki
H
Kobayashi
Mayumi
M
Takasaki
Akihiko
A
Wada
D000311:Adrenal Glands / Q000166:cytology*; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002395:Catecholamines / Q000378:metabolism; D002417:Cattle; D002478:Cells, Cultured; D019439:Chromaffin Cells / Q000187:drug effects*; D004791:Enzyme Inhibitors / Q000494:pharmacology; D008246:Lysophospholipids / Q000494:pharmacology; D008564:Membrane Potentials / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D018408:Patch-Clamp Techniques / Q000379:methods; D012333:RNA, Messenger / Q000378:metabolism; D011868:Radioisotopes / Q000378:metabolism; D049368:Receptors, Lysophosphatidic Acid / Q000502:physiology; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology*; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000235:genetics* / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects*; D014701:Veratridine / Q000494:pharmacology; D020741:rho GTP-Binding Proteins / Q000502:physiology; D054460:rho-Associated Kinases / Q000502:physiology
D002395:Catecholamines; D004791:Enzyme Inhibitors; D008246:Lysophospholipids; D012333:RNA, Messenger; D011868:Radioisotopes; D049368:Receptors, Lysophosphatidic Acid; D015222:Sodium Channels; D014701:Veratridine; D012964:Sodium; D054460:rho-Associated Kinases; D020741:rho GTP-Binding Proteins; C032881:lysophosphatidic acid; D002118:Calcium