Continuous monitoring of catecholamine release from perfused cat adrenals.

Catecholamine release from perfused cat adrenal glands has been continuously monitored by on-line connection of the perfusion fluid emanating from the gland to an electrochemical detector. This method allowed: the recording of basal levels and fluctuations of catecholamine release with good reliability; the study of the release of catecholamines in response to even submicromolar concentrations of nicotine or acetylcholine and 3 mM increments of the K+ concentration, perfused in pulses of a few seconds, and to determine the effects of drugs and ionic manipulations on such secretory responses; the analysis of the 'physiological' secretory response evoked by electrical stimulation of the splanchnic nerves, allowing the study of presynaptic as well as postsynaptic components of the effects of drugs and ions on chemical neurotransmission at the splanchnic--chromaffin cell synapse; the continuous monitoring of the kinetics of the secretory process during sustained depolarization with several secretagogues and its correlation with the kinetics of activation and inactivation of potential sensitive Ca channels. In addition, this method avoids the time-consuming procedures of collecting samples and assaying them individually through tedious fluorimetric or radioenzymatic techniques.