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Multiple modulatory effects of dopamine on calcium channel kinetics in adult rat sensory neurons
Author(s) -
Formenti Alessandro,
Martina Marzia,
Plebani Alessio,
Mancia Mauro
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.395bn.x
Subject(s) - dopamine , sensory system , neuroscience , chemistry , calcium , kinetics , calcium channel , t type calcium channel , biophysics , medicine , biology , physics , quantum mechanics
1 The aim of this research was to study the modulatory effects induced on high‐voltage‐activated (HVA) calcium channels and pharmacologically isolated subtypes through dopamine receptor activation. 2 The experiments were carried out on acutely isolated adult rat sensory neurons, recorded by means of the whole‐cell patch‐clamp technique. 3 At saturating concentrations dopamine was effective in inducing: (a) a voltage‐dependent prolongation of activation kinetics, (b) a voltage‐independent scaling down of the currents without any changes in activation and inactivation kinetics, and (c) an acceleration of inactivation kinetics, not affected by a positive conditioning prepulse. 4 These three inhibitory effects were observed on N‐ and P/Q‐type currents, whereas only a voltage‐independent scaling up and/or scaling down was observed on L‐type current. 5 The inhibitory effects were sometimes observed in isolation in different neurons, but more frequently they were variously combined in the same cell. A correlation analysis of these effects shows no relationship between them, corroborating the conclusion that they are mechanistically distinct. 6 The existence of an inactivating effect accounts for the occurrence of a voltage‐dependent inhibitory effect in some cells without an apparent slowing down of activation kinetics, since the increased inactivation may mask the slow component of the activation. 7 The multiple modulatory effects on calcium channels, even on pharmacologically separated N‐, L‐ and P/Q‐currents, suggest that pharmacological and functional classifications do not necessarily match completely. 8 The multiple modulatory effects on HVA calcium currents may play a prominent role both in controlling the integrative properties of neurons and in regulating output at a presynaptic level.