Answers are grounded in this paper and cite their sources.
Cerebrovascular permeability of four modified opioid peptides--[D-Ala2]methionine enkephalin amide, beta-[D-Ala62,14C-Homoarg69]lipotropin 61 -69, alpha-[D-Ala2,14C-Homoarg9]endorphin, and beta-[D-Ala2,14C-Homoarg]endorphin--ranged from 1.4 to 3.9 X 10(-6) centimeters per second in brain regions of the conscous rat. These significant permeabilities should allow the peptides to fill the extracellular brain space with a half time of 3 to 11 minutes, as a result of a step increase in plasma concentration of unbound peptide.
No takes yet. Share an insight, caveat, or question.
Рапопорт et al. (1980) studied this question.
Synapse has enriched 10 related papers. Consider them for comparative context: