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Dopamine release and metabolism in DAergic cell-grafted caudate nucleus in the rat
s122
DOPAMINE RELEASE AND METABOLISM IN DAeraic CELL-GRAFTED CAUDATE NUCLEUS IN THE RAT. TAKESHI HASHITANI, MICHIKO KUMAZAKI, TERUMI SAKURAI, ISOBE YOSIAKI, FUJIYA FURUYAMA, HARUHIKO SAT0 AND HIT00 NISHINO. Department of Physiology, Nagoymy University Medical School, Mlzuho-ku, y Nagoya 467, Japan. A suspension of fetal niaral DAeraic cells was arafted to the caudate nucleus of rats with unilateral lesions in
ACTIONS OY ADENOSINE ON SPONTANEOUS OR EVOKED TRAMSMITTER RELEASE AT THE FROG NEUROMUSCULAR JUNCTION. YORIKO TAKIKAWA, AND NORIKO TAKEUCHI. Department of Physiology, Juntendo University School of Medicin, 2-l-l Hongo, Bunkyou-ku, Tokyo 113, Japan. The inhibitory effects of adenosine on spontaneous and evoked transmitter release were investigated at the frog neuromuscular junction. Applied adenosine reduced both spontaneous (MEPP) and evoked (EPP) quanta1 release dosedependently. In normal and high (12mM) K'solutions, the degree of inhibition on MEPP frequency produced by adenosine was not markedly changed in a wide range of external Ca'concentrations (O.l-7.2mM1, even in solution containing no added Ca and lmM-EGTA. When the spontaneous release included sub-MEPP or giant MEPP, addition of ademosine did not alter the sub-MEPP and giant MEPP frequencies but selectively decreased the normal mode MEPP frequency. Application of adenosine deaminase slightly increased both spontaneous and evoked transmitter release, while the enzyme application appeared to have no apparent effect in some cases of high K*solution. These results suggest the possibilities that 1) the depressant effects of adenosine are not mainly caused by reducing Ca"influx into the nerve terminals, 2) there is a release site that is unaffected by adenosine, might 3) endogenous adenosine concentration and adenosine deaminase activity vary from preparation to preparation.
Ca ++-INDEPENDENT
JUNCTION: Daiichi Faculty
REGULATION
OF TRANSMITTER
NORIKO TANABE*‘, __--
2ND REPORT.
College
RELEASE
of Pharmaceutical Sciences, -of Science, Kyushu University, Fukuoka 812, Japan.
Four processesof stimulation-induced increasein transmitter neuromuscular tentiation, BAPTA facilitation
AT THE FROG NEUROMUSCULAR
AND HIROMASA MKIMA’ of Biology, ----__ -- , ‘Department Fukuoka 815, and ‘Department ~ -of Biology,
junction occur
(Tanabe
(NMJ).
independently and Kijima,
was completely
We reported of internal
Neurosci.
Lett.
release
have been known at the frog
last year that two slower processes, augmentation and po++ ++ by making use of the NMJ loaded with a Ca -chelator Ca , 99,
147, 1989).
lost at the BAPTA-loaded
Among
two other
faster
processes,
the fast
NMJ, while magnitude of the slow facilitation was
unchanged and itsdecaying time constant was a littleincreased,compared with the normal NMJ. The Ca ++-freeconditions(+EGTA augmentation and potentiationof MEPP frequency observed under external 1 mM) were also littlechanged at the BAPTA-loaded NMJ.
Three slower stimulation-induced increasesof
transmitterreleasewere stronglysuggested to be caused independentlyof the internalCaf+ at the releasmg site. Dual release-regulating systems may exist at the NMJ, as well as in the mast cell.
DOPAMINE RELEASE AND METABOLISM IN DAeraic CELL-GRAFTED CAUDATE NUCLEUS IN THE RAT. TAKESHI HASHITANI, MICHIKO KUMAZAKI, TERUMI SAKURAI, ISOBE YOSIAKI, FUJIYA FURUYAMA, HARUHIKO SAT0 AND HIT00 NISHINO. Department of Physiology, Nagoymy University Medical School, Mlzuho-ku, y Nagoya 467, Japan. A suspension of fetal niaral DAeraic cells was arafted to the caudate nucleus of rats with unilateral lesions in
ACTIONS OY ADENOSINE ON SPONTANEOUS OR EVOKED TRAMSMITTER RELEASE AT THE FROG NEUROMUSCULAR JUNCTION. YORIKO TAKIKAWA, AND NORIKO TAKEUCHI. Department of Physiology, Juntendo University School of Medicin, 2-l-l Hongo, Bunkyou-ku, Tokyo 113, Japan. The inhibitory effects of adenosine on spontaneous and evoked transmitter release were investigated at the frog neuromuscular junction. Applied adenosine reduced both spontaneous (MEPP) and evoked (EPP) quanta1 release dosedependently. In normal and high (12mM) K'solutions, the degree of inhibition on MEPP frequency produced by adenosine was not markedly changed in a wide range of external Ca'concentrations (O.l-7.2mM1, even in solution containing no added Ca and lmM-EGTA. When the spontaneous release included sub-MEPP or giant MEPP, addition of ademosine did not alter the sub-MEPP and giant MEPP frequencies but selectively decreased the normal mode MEPP frequency. Application of adenosine deaminase slightly increased both spontaneous and evoked transmitter release, while the enzyme application appeared to have no apparent effect in some cases of high K*solution. These results suggest the possibilities that 1) the depressant effects of adenosine are not mainly caused by reducing Ca"influx into the nerve terminals, 2) there is a release site that is unaffected by adenosine, might 3) endogenous adenosine concentration and adenosine deaminase activity vary from preparation to preparation.
Ca ++-INDEPENDENT
JUNCTION: Daiichi Faculty
REGULATION
OF TRANSMITTER
NORIKO TANABE*‘, __--
2ND REPORT.
College
RELEASE
of Pharmaceutical Sciences, -of Science, Kyushu University, Fukuoka 812, Japan.
Four processesof stimulation-induced increasein transmitter neuromuscular tentiation, BAPTA facilitation
AT THE FROG NEUROMUSCULAR
AND HIROMASA MKIMA’ of Biology, ----__ -- , ‘Department Fukuoka 815, and ‘Department ~ -of Biology,
junction occur
(Tanabe
(NMJ).
independently and Kijima,
was completely
We reported of internal
Neurosci.
Lett.
release
have been known at the frog
last year that two slower processes, augmentation and po++ ++ by making use of the NMJ loaded with a Ca -chelator Ca , 99,
147, 1989).
lost at the BAPTA-loaded
Among
two other
faster
processes,
the fast
NMJ, while magnitude of the slow facilitation was
unchanged and itsdecaying time constant was a littleincreased,compared with the normal NMJ. The Ca ++-freeconditions(+EGTA augmentation and potentiationof MEPP frequency observed under external 1 mM) were also littlechanged at the BAPTA-loaded NMJ.
Three slower stimulation-induced increasesof
transmitterreleasewere stronglysuggested to be caused independentlyof the internalCaf+ at the releasmg site. Dual release-regulating systems may exist at the NMJ, as well as in the mast cell.