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AXONAL TRANSPORT OF PHENYLETHANOLAMINE‐ N ‐METHYLTRANSFERASE IN TOAD SCIATIC NERVE
Author(s) -
Wooten G. F.,
Saavedra J. M.
Publication year - 1974
Publication title -
journal of neurochemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.75
H-Index - 229
eISSN - 1471-4159
pISSN - 0022-3042
DOI - 10.1111/j.1471-4159.1974.tb04337.x
Subject(s) - toad , sciatic nerve , chemistry , endocrinology , medicine , ligation , bufo marinus , phenylethanolamine n methyltransferase , enzyme , anatomy , biology , biochemistry , phenylethanolamine , tyrosine hydroxylase
—The presence of phenylethanolamine‐ N ‐methyltransferase (EC 2.1.1.‐) and dopamine‐β‐hydroxylase (EC 1.14.2.1) activities was demonstrated in the sciatic nerve of the toad, Bufo marinus. The rates of accumulation of phenylethanolamine‐ N ‐methyltransferase (PNMT) and dopamine‐β‐hydroxylase (DBH) proximal to a ligation of the sciatic nerve were studied. DBH accumulated proximal to the ligation at a more than 10‐fold faster rate than PNMT. By measuring the rate of loss of enzyme activity distal to a ligation, an estimate of per cent clearance of each enzyme was made. Based on the per cent of enzyme activity free to move, the absolute transport rates for each enzyme were estimated to be: PNMT, 3.6 mm/24 h; DBH, 102 mm/24 h. PNMT activity (89 per cent) was recovered in the soluble fraction of sciatic nerve homogenates with no change occurring in the subcellular distribution of the enzyme proximal to ligations. In contrast, 43 per cent of DBH activity was found in the soluble fraction of sciatic nerve homogenates; but a disproportionate increase in paniculate DBH activity was found proximal to sciatic nerve ligations. Reduction of toad body temperature to 4°C resulted in a complete but totally reversible block of the axonal transport of both PNMT and DBH.