On treatment with collagenase, brain microvessels, together with several protein components, lose some enzymatic activities such as alkaline phosphatase and gamma-glutamyltranspeptidase, whereas no change occurs in the activities of 5'-nucleotidase and glutamine synthetase. The energy-requiring "A-system" of polar neutral amino acid transport is also severely inactivated, whereas the L-system for the facilitated exchange of branched chain and aromatic amino acids is preserved. In the collagenase-digested microvessels, this leads to loss of the transtimulation effect of glutamine on the transport of large neutral amino acids, because such transtimulation is due to a cooperation between the A- and L-systems. By contrast, NH4+ maintains (and even enhances) its ability to stimulate the L-system of amino acid transport, presumably through glutamine synthesis within the endothelial cells. Amino acid transport, Blood-Brain Barrier, Brain microvessels, Collagenase digestion, Glutamine synthetase, Transtimulation
Isolated brain microvessels as in vitro equivalents of the blood-brain barrier: selective removal by collagenase of the A-system of neutral amino acid transport / Cardelli, Patrizia; Fiori, Anna; Cangiano, Carlo Oreste; Barberini, Fabrizio; Allegra, Paola; Peresempio, V; Strom, Roberto. - In: JOURNAL OF NEUROCHEMISTRY. - ISSN 0022-3042. - STAMPA. - 49:6(1987), pp. 1667-1675. [10.1111/j.1471-4159.1987.tb02424.x]
Isolated brain microvessels as in vitro equivalents of the blood-brain barrier: selective removal by collagenase of the A-system of neutral amino acid transport
CARDELLI, Patrizia;FIORI, Anna;CANGIANO, Carlo Oreste;BARBERINI, Fabrizio;ALLEGRA, Paola;STROM, Roberto
1987
Abstract
On treatment with collagenase, brain microvessels, together with several protein components, lose some enzymatic activities such as alkaline phosphatase and gamma-glutamyltranspeptidase, whereas no change occurs in the activities of 5'-nucleotidase and glutamine synthetase. The energy-requiring "A-system" of polar neutral amino acid transport is also severely inactivated, whereas the L-system for the facilitated exchange of branched chain and aromatic amino acids is preserved. In the collagenase-digested microvessels, this leads to loss of the transtimulation effect of glutamine on the transport of large neutral amino acids, because such transtimulation is due to a cooperation between the A- and L-systems. By contrast, NH4+ maintains (and even enhances) its ability to stimulate the L-system of amino acid transport, presumably through glutamine synthesis within the endothelial cells. Amino acid transport, Blood-Brain Barrier, Brain microvessels, Collagenase digestion, Glutamine synthetase, TranstimulationI documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.