Amino acid transport in human ciliary epithelium

A statistical study of the co-variation of the concentrations of 19 amino acids and related compounds from 21 persons was performed as a factor analysis of Caq/Cpl and of Caq. Six factors explained about 83% of the observed variation. Factor 1 showed a correlation to alpha-amino-N-butyric acid, valine, methionine, isoleucine, leucine, tyrosine and phenylalanine, factor 2 to lysine, histidine, arginine and glutamine (containing serine), factor 3 to taurine and proline, factor 4 to glycine and cystine, factor 5 to urea and factor 6 to glutamic acid. Only alanine and threonine showed a correlation to different factors in the Caq/Cpl- and the Caq-matrix. This correlation of groups of substances to different and independent factors is considered to be an argument in favour of the existence of six transport systems in the ciliary epithelium for the investigated substances.