Voltage-dependent calcium currents in bulbospinal neurons of neonatal rat rostral ventrolateral medulla: modulation by alpha2-adrenergic receptors.

Li YW, Guyenet PG, Bayliss DA. J Neurophysiol. 1998 Feb;79(2):583-94 I picked this paper because we're currently using manganese to probe for activity-dependent MRI contrast enhancment in the RVLM. Manganese is known to enter neurons during action potential, primarily through L-type voltage-gated calcium channels. I wanted to know a little more about the presence of these channels on the neurons we study, and this paper has a breakdown of of different calcium channels' relative contributions to the overall calcium currents. Neonatal rats were given retrograde tracers in the spinal cord in order to label the bulbospinal neurons of the RVLM. 3-5 days later, 150um slices of their brainstems were taken and labeled cells were recorded by patch-clamp. Calcium currents were recorded under voltage clamp, and the different types of channels were drugged out in order to identify channel type contributions. What they found was that N-type channels made up 38%, P/Q-type made up 30%, and our favorite L-type only made up 8% So the big question I'm left with, is that 8% enough for us to see? I guess I should have faith in the fact that 150um slices may not have quite as many calcium channels as whole cells in vivo. -DH