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 .
C0205753
opioid
C0014242
endorphin