Butanol isomers exert distinct effects on voltage-gated calcium channel currents and thus catecholamine secretion in adrenal chromaffin cells

• Published in: PloS one Vol. 9; no. 10; p. e109203
• Main Authors: McDavid, Sarah, Bauer, Mary Beth, Brindley, Rebecca L, Jewell, Mark L, Currie, Kevin P M
• Format: Journal Article
• Language: English
• Published: United States Public Library of Science 02.10.2014; Public Library of Science (PLoS)
• Subjects: Acids; Adrenal glands; Alcohol; Alcohols; Anesthesiology; Anesthetics; Animals; Bauer, Beth; Biology and Life Sciences; Butanol; Butanols - chemistry; Butanols - pharmacology; Calcium; Calcium - metabolism; Calcium channels; Calcium channels (voltage-gated); Calcium Channels - drug effects; Calcium currents; Carbon; Catecholamine; Catecholamines; Catecholamines - secretion; Cattle; Channel gating; Chromaffin cells; Chromaffin Cells - drug effects; Chromaffin Cells - secretion; Degranulation; Depolarization; Electrophysiology; Exocytosis; Fluorescence; Fluoroscopic imaging; Inhibitors; Insulin; Intracellular signalling; Ion Channel Gating; Isomerism; Isomers; Kinases; Kinetics; Ligands; Mast cells; Medical research; Medicine; Pharmacology; Phosphatidic acid; Phospholipase; Phospholipase D; Phospholipases; Secretion; Substrates; Telomerase; Tert-butanol; United States > US; Tennessee; Nashville Tennessee
• ISSN: 1932-6203; 1932-6203
• DOI: 10.1371/journal.pone.0109203

Butanol (C4H10OH) has been used both to dissect the molecular targets of alcohols/general anesthetics and to implicate phospholipase D (PLD) signaling in a variety of cellular functions including neurotransmitter and hormone exocytosis. Like other primary alcohols, 1-butanol is a substrate for PLD and thereby disrupts formation of the intracellular signaling lipid phosphatidic acid. Because secondary and tertiary butanols do not undergo this transphosphatidylation, they have been used as controls for 1-butanol to implicate PLD signaling. Recently, selective pharmacological inhibitors of PLD have been developed and, in some cases, fail to block cellular functions previously ascribed to PLD using primary alcohols. For example, exocytosis of insulin and degranulation of mast cells are blocked by primary alcohols, but not by the PLD inhibitor FIPI. In this study we show that 1-butanol reduces catecholamine secretion from adrenal chromaffin cells to a much greater extent than tert-butanol, and that the PLD inhibitor VU0155056 has no effect. Using fluorescent imaging we show the effect of these drugs on depolarization-evoked calcium entry parallel those on secretion. Patch-clamp electrophysiology confirmed the peak amplitude of voltage-gated calcium channel currents (I(Ca)) is inhibited by 1-butanol, with little or no block by secondary or tert-butanol. Detailed comparison shows for the first time that the different butanol isomers exert distinct, and sometimes opposing, effects on the voltage-dependence and gating kinetics of I(Ca). We discuss these data with regard to PLD signaling in cellular physiology and the molecular targets of general anesthetics.