Activity-dependent changes in intracellular calcium in myenteric neurons.
The spatial distribution and changes in intracellular calcium concentration ([Ca2+]i) in myenteric neurons were measured using fura 2 in the longitudinal muscle-myenteric plexus preparation from the guinea pig duodenum. These measurements were made simultaneously with intracellular voltage recordings. The generation of action potentials in the cell bodies of both S- and AH-type neurons increased [Ca2+]i in the processes and cell bodies. There was no measurable delay between the [Ca2+]i changes in the somata and the processes, indicating that these changes were caused by the spread of electrical signals and not by diffusion. The rate of Ca2+ removal was faster in the processes than in the somata, apparently due to the large surface-to-volume ratio in the former. In AH neurons, the [Ca2+]i transient was shorter than the duration of the after-spike hyperpolarization. It is concluded that the two main types of myenteric neurons possess voltage-gated Ca2+ channels in both somata and processes.
Hanani
M
M
Hebrew University-Hadassah Medical School, Jerusalem, Israel.
Lasser-Ross
N
N
D000200:Action Potentials / Q000502:physiology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels / Q000502:physiology*; D003600:Cytosol / Q000378:metabolism; D004386:Duodenum / Q000294:innervation / Q000502:physiology*; D016257:Fura-2; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007700:Kinetics; D008297:Male; D009130:Muscle, Smooth / Q000294:innervation / Q000502:physiology*; D009197:Myenteric Plexus / Q000502:physiology*; D009474:Neurons / Q000502:physiology*
D015220:Calcium Channels; D002118:Calcium; D016257:Fura-2