Influence of alpha-methyldopa treatment on adrenergic receptor binding in rat forebrain.
We studied the influence of 6 days treatment with alpha-methyldopa (50 mg/kg s.c.) twice daily on radioligand binding to alpha 1 [3H)prazosin), alpha 2 [3H)clonidine) and beta[3H)dihydroalprenolol (DHA] receptors in rat forebrain. A 27% rise (p less than 0.05) in the Bmax for (3H)prazosin without change in Kd was found. Following alpha-methyldopa, the Kd for (3H)clonidine was increased from 1.78 +/- 19 to 3.03 +/- nM and Bmax fell from 197 +/- 20 to 167 +/- 19 fmoles/mg protein (p less than 0.05). These findings suggest that chronic alpha-methyldopa therapy induces changes in alpha 1 and alpha 2 receptors which may modify the antihypertensive effect of alpha-methyldopa.
D000818:Animals; D001921:Brain / Q000187:drug effects* / Q000378:metabolism; D003000:Clonidine / Q000378:metabolism; D004082:Dihydroalprenolol / Q000378:metabolism; D008297:Male; D008750:Methyldopa / Q000494:pharmacology*; D011224:Prazosin / Q000378:metabolism; D011869:Radioligand Assay; D051381:Rats; D011919:Rats, Inbred Strains; D011941:Receptors, Adrenergic / Q000187:drug effects* / Q000378:metabolism; D014316:Tritium
D011941:Receptors, Adrenergic; D014316:Tritium; D008750:Methyldopa; D004082:Dihydroalprenolol; D003000:Clonidine; D011224:Prazosin