Distinguishing splanchnic nerve and chromaffin cell stimulation in mouse adrenal slices with fast-scan cyclic voltammetry

Abstract

Electrical stimulation is an indispensible tool in studying electrically excitable tissues in neurobiology and neuroendocrinology. In this work, the consequences of high-intensity electrical stimulation on the release of catecholamines from adrenal gland slices were examined with fast-scan cyclic voltammetry at carbon fiber microelectrodes. A biphasic signal, consisting of a fast and slow phase, was observed when electrical stimulations typically used in tissue slices (10 Hz, 350 μA biphasic, 2.0 ms/phase pulse width) were applied to bipolar tungsten-stimulating electrodes. This signal was found to be stimulation dependent, and the slow phase of the signal was abolished when smaller (≤250 μA) and shorter (1 ms/phase) stimulations were used. The slow phase of the biphasic signal was found to be tetrodotoxin and hexamethonium independent, while the fast phase was greatly reduced using these pharmacological agents. Two different types of calcium responses were observed, where the fast phase was abolished by perfusion with a low-calcium buffer while both the fast and slow phases could be modulated when Ca²(+) was completely excluded from the solution using EGTA. Perfusion with nifedipine resulted in the reduction of the slow catecholamine release to 29% of the original signal, while the fast phase was only decreased to 74% of predrug values. From these results, it was determined that high-intensity stimulations of the adrenal medulla result in depolarizing not only the splanchnic nerves, but also the chromaffin cells themselves resulting in a biphasic catecholamine release.

Spatial and activity-dependent catecholamine release in rat adrenal medulla under native neuronal stimulation

“…) and for the detection of bulk catecholamine release from mouse adrenal slices (Walsh et al. ). Here, we extend this technique by calibrating signals against standard solutions and by separating signal characteristic for catecholamine species in an ex vivo, intact splanchnic–adrenal experimental preparation.…”

“…We adapted a fast scanning cyclic voltammetry (FSCV) method for measuring separately the release of epinephrine (Epi) and norepinephrine (NE) under native neuronal stimulation. FSCV has been used to qualitatively measure release of catecholamine species from isolated bovine chromaffin cells (Pihel et al 1994) and for the detection of bulk catecholamine release from mouse adrenal slices (Walsh et al 2011). Here, we extend this technique by calibrating signals against standard solutions and by separating signal characteristic for catecholamine species in an ex vivo, intact splanchnic-adrenal experimental preparation.…”

Ultrafast Detection and Quantification of Brain Signaling Molecules with Carbon Fiber Microelectrodes

“…Wightman and colleagues have recently shown that this process is modulated by specialized receptors . Moreover, they have shown that amperometry can distinguish between signals arising from unselective electrical stimulations (cells vs peripheral nerves) …”

Fast in vivo detection of myocardial norepinephrine levels in the beating porcine heart

“…In this study, a novel adaptation of a dynamic approach for electrochemical detection of NE levels in vivo is presented. The approach is based on fast scanning cyclic voltammetry (FSCV), a method utilized to measure catecholamine release from isolated cells ( 21 , 25 ) or from tissues ( 16 , 30 , 33 ). Briefly, an electrode is placed near the source of the transmitter and its potential driven though the oxidation/reduction potentials by a voltage clamp circuit.…”