摘要:

AbstractA significant activation of tryptophan hydroxylase (TPH) was achieved by the addition of 1 mM ATP and 10 mM MgCl2to 100,000g supernatant prepared from mouse midbrain. The activation produced an increase of enzyme activity by 50–70% above control. Cyclic AMP was not a necessary component in the activation as initially suspected; neither was the involvement of a cyclic AMP‐dependent protein kinase detected. The enzyme activation by Mg+2‐ATP was totally retained after dialysis, thus excluding the possibility of an allosteric effect. In contrast to the activation, TPH was found to be sensitive to inactivation by acid phosphatase, a dephosphorylating enzyme. These findings are consistent with the proposal that the enzyme activation may involve a phosphorylation process. Furthermore, the activation by Mg+2‐ATP in the brain preparations was only minimally observed from neonatal mice and could be abolished from adult mice by administration of hydrocortisone. It appears that the phosphorylation process, as postulated here, may be under developmental and hormonal inf

ISSN:0360-4012    

DOI:10.1002/jnr.490030512

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe distribution of acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) has been investigated in a series of sections passing through the medulla oblongata and pons of the squirrel brain. A comparison of the two enzymes has given an interesting picture of their selective localization in the different nuclei. Marked AChE activity has been observed in the cranial nerve nuclei. BChE activity in various nuclei of the medulla oblongata and pons is variable and occurs diffusely between the cells. Possible reasons pertaining to marked variation in AChE and BChE contents of various nuclei and fiber tracts have been discussed.

ISSN:0360-4012    

DOI:10.1002/jnr.490030513

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

摘要:

AbstractThe dependance of the reversal potential (Erev) of intracellular end‐plate potentials (epp) on activity patterns was studied in frog neuromuscular preparations. A shift of Erev to the positive side was found with change in frequency of stimulation from 1/sec to 50/sec. This shift corresponds to the increase of potassium concentration in the synaptic cleft to 7.0 mM. The effect of potassium concentration [K+]0in the bath solution on quantal content (m) of epp was studied. The quantity m increased when [K+]0was varied within the range 4.7–8.7 mM; m decreased when [K+]0was>8.7 mM. Such a relationship between m and [K+]0is accounted for by the combined effect of potassium on transmitter secretion and electrongenic processes in motor nerve terminals.The correlation between the change of m with [K+]0and initial epp amplitudes was found and was attributed to potassium efflux from post‐synaptic region in varying quantity depending on the initial epp amplitudes. A scheme of synaptic self‐regulation by means of potassium feedback is su

ISSN:0360-4012    

DOI:10.1002/jnr.490030514

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY

ISSN:0360-4012    

DOI:10.1002/jnr.490030501

出版商:Wiley Subscription Services, Inc., A Wiley Company    

年代:1978

数据来源: WILEY