Identification of two calcium currents in acutely dissociated neurons from the rat lateral geniculate nucleus.

摘要: 1. Intracellular recording in the vitro slice preparation and whole-cell, patch-clamp of acutely dissociated neurons from rat lateral geniculate nucleus (LGN) were combined to study Ca currents underlying their electrical responses. In slices young animals (postnatal days 13-16), we found that dorsal LGN have responses similar those adult preparations, including presence a low-threshold spike (LTS). After enzymatic isolation same animals, firing properties appeared well preserved, as indicated by current-clamp recordings multipolar cells (presumably geniculocortical relay neurons). 2. Two types identified voltage-clamped, isolated on basis voltage dependency, pharmacology, selectivity properties. These two resemble low-voltage-activated (LVA) high-voltage-activated (HVA) channels sensory (9). 3. The LVA current component required negative potentials (less than -80 mV) deinactivate completely, started activate around -60 mV reached plateau level -25 mV. It peaked within 30-6 ms decayed with single time constant approximately 24 at -20 Its inactivation curve ranged -100 -40 mV, half-inactivation near HVA could be holding membrane potential positive activated -30 +5 time-to-peak 30 6 range +35 very slowly sustained depolarizing pulses (time between 1,600 40 over range). 4. during steps was consistent voltage-dependent process. recovery after short (100 ms), inactivating prepulses displayed exponential phases. slower phase predominant under conditions induce large flow through membrane, suggesting Ca-mediated mechanism. 5. preferentially blocked 50 microM Ni2+, leaving almost unaltered. Fifty micromolars Cd2+, contrast, seemed more effective blocking current.(ABSTRACT TRUNCATED AT 400 WORDS)