Effects of serotonin and carbachol on glial and neuronal rubidium uptake in leech CNS.
Effects of serotonin (5-HT) and carbachol on Rb uptake (used as a K marker) in leech neuron and glia were studied by electron probe microanalysis (EPMA). Hirudo medicinalis ganglia were perfused 60 s in 4 mM Rb substituted normal leech Ringer's with and without 5-HT (dosage range 5-500 microM) or carbachol (range 10-1000 microM), quench frozen cryosectioned, and subjected to EPMA to determine elemental mass fractions and cell water content. Both 5-HT and carbachol altered leech neuron and glial cell elemental distribution and water content. In glial cells, a dose-dependent increase in Rb uptake was observed following 5-HT (control: 26 +/- 2 microM; 5 microM: 47 +/- 4; 50 microM: 62 +/- 4; 500 microM: 82 +/- 11 mmol/kg dry wt. +/- S.E.M.) and carbachol (10 microM: 35 +/- 3; 100 microM: 52 +/- 3; 1000 microM: 68 +/- 3 mmol/kg dry wt. +/- S.E.M.). In neurons, 5-HT and carbachol had small effects. 5-HT decreased glial and neuronal cell water content. Carbachol decreased neuronal (but not glial) water content by approximately the same amount (mean decrease 9%) regardless of dose. Both 5-HT and carbachol affected glial cell K-accumulating properties, providing evidence that certain neurotransmitters may modulate invertebrate glial cells' K clearance function.
Foster
M C
MC
Department of Anesthesiology, School of Medicine, SUNY, Stony Brook 11794-8480.
Castiglia
C M
CM
Saubermann
A J
AJ
D000818:Animals; D001834:Body Water / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology*; D002490:Central Nervous System / Q000187:drug effects / Q000378:metabolism; D002712:Chlorides / Q000378:metabolism; D007865:Leeches / Q000187:drug effects* / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects* / Q000378:metabolism; D009474:Neurons / Q000187:drug effects* / Q000378:metabolism; D011188:Potassium / Q000378:metabolism; D012413:Rubidium / Q000378:metabolism*; D012701:Serotonin / Q000494:pharmacology*; D012964:Sodium / Q000378:metabolism
D002712:Chlorides; D012701:Serotonin; D002217:Carbachol; D012964:Sodium; D012413:Rubidium; D011188:Potassium