Optical mapping of pontine chemosensitive regions of neonatal rat.
We analyzed the neuronal response to hypercapnic acidosis, using an optical recording technique with a fluorescent voltage-sensitive dye (di-4-ANEPPS), in pontine slice preparations of neonatal rats, containing the locus coeruleus (LC), which has been electrophysiologically demonstrated to be chemosensitive. The dye-stained preparation was continuously superfused with artificial cerebrospinal fluid. Epifluorescence of the slice was detected using a high-sensitivity optical recording system. Changes in the intensity of fluorescence were serially analyzed while switching artificial cerebrospinal fluid from control to hypercapnic acidosis, or vice versa. The optical recording method revealed that the LC, as reported in previous studies, reversibly showed a depolarizing response to hypercapnic acidosis in 56% of the examined preparations. The A5 area (56%) also exhibited a reversible, depolarizing response to hypercapnic acidosis. The response was preserved under conditions in which chemical synaptic transmission was blocked by low Ca(2+)-high Mg(2+) solution. These results suggest that the optical recording method is applicable to identification of potentially chemosensitive areas, which deserve further electrophysiological analysis, and that the A5 area could be chemosensitive.
Ito
Yoko
Y
Department of Medicine, School of Medicine, Keio University, 35 Shinano-machi, Shinjuku-ku, Tokyo 160-8582, Japan.
Oyamada
Yoshitaka
Y
Okada
Yasumasa
Y
Hakuno
Haruhiko
H
Aoyama
Ryoma
R
Yamaguchi
Kazuhiro
K
D000138:Acidosis / Q000503:physiopathology; D000818:Animals; D000831:Animals, Newborn; D004560:Electricity; D005456:Fluorescent Dyes; D006863:Hydrogen-Ion Concentration; D006935:Hypercapnia / Q000503:physiopathology*; D066298:In Vitro Techniques; D008125:Locus Coeruleus / Q000503:physiopathology; D055095:Optics and Photonics; D011149:Pons / Q000503:physiopathology*; D011726:Pyridinium Compounds; D051381:Rats
D005456:Fluorescent Dyes; D011726:Pyridinium Compounds; C050019:1-(3-sulfonatopropyl)-4-(beta)(2-(di-n-butylamino)-6-naphthylvinyl)pyridinium betaine