ABSTRACT
Cats were sacrificed 1-3 weeks after cervical (C1-C2) hemisection and receptor binding experiments were carried out with 4.0 and 0.6 nM concentrations of [3H]dihydromorphine [( 3H]DHM); these concentrations were shown by Scatchard analysis to represent the approximate Kd values of high and low affinity dihydromorphine binding sites in brain homogenates. Unilateral cervical hemisection produced significant (P less than 0.05), bilateral, reductions in the levels of [3H]DHM binding in the periaqueductal gray (PAG; 35-40%) and mesencephalic reticular formation (MRF; 47-51%), medial pons (40-56%) and medial medulla (30-37%). In paramedial pons and medulla, numerical reductions in [3H]DHM binding were observed (18 and 28%) which did not achieve statistical significance. In spinal cord, significant reductions were observed in the dorsal (45%) and ventral (29%) ipsilateral but not contralateral quadrants. We believe that these results in the brainstem and spinal cord reflect in part the loss of opiate binding on spinobulbar terminals and bulbospinal terminals, respectively, following orthograde degeneration. These observations support the hypothesis that the analgetic effects of opiates in the brainstem may in part be mediated by the direct inhibition of transmission through spinobulbar terminals.
Subject(s)
Brain Stem/metabolism , Dihydromorphine/metabolism , Morphine Derivatives/metabolism , Receptors, Opioid/metabolism , Spinal Cord/metabolism , Animals , Brain Stem/cytology , Cats , Neural Pathways/metabolism , Spinal Cord/cytologyABSTRACT
The specific activity of argininosuccinate synthetase (micromoles of 14CO2 per milligram of protein per hour) was 0.00104 and 0.00087 in fibroblasts derived from two patients with citrullinemia, and was undetectable in both fibroblasts and cultured lymphocytes from a third patient. In five obligate heterozygotes the specific activity in fibroblasts was 0.012-0.029 and in nine control subjects was 0.058 +/- 0.014 (0.030-0.076). In both control and patient cells, the maximum activity was obtained at pH 8.5 and there was no inhibition of normal argininosuccinate synthetase by any of the mutant cells.
