1: Am J Hypertens. 2004 Aug;17(8):712-7. 

Cyclic strain stimulates L-proline transport in vascular smooth muscle cells.

Reyna SV, Ensenat D, Johnson FK, Wang H, Schafer AI, Durante W.

Michael E. DeBakey VA Medical Center, Houston, Texas 77030, USA.

BACKGROUND: The increase in vessel wall strain in hypertension contributes to
arterial remodeling by stimulating vascular smooth muscle cell (SMC)
proliferation and collagen synthesis. Because L-proline is essential for the
synthesis of collagen and cell growth, we examined whether cyclic strain
regulates the transcellular transport of L-proline by vascular SMC. METHODS:
Cultured rat aortic SMCs were subjected to mechanical strain using the
Flexercell 3000 Strain Unit. RESULTS: Cyclic strain increased L-proline
transport in a time- and strain-degree-dependent manner that was inhibited by
cycloheximide or actinomycin D. Kinetic studies indicated that cyclic
strain-induced L-proline uptake was mediated by an increase in transport
capacity independent of any change in the affinity for L-proline. Cyclic strain
stimulated the expression of system A amino acid transporter 2 mRNA in a
time-dependent fashion that paralleled the increase in L-proline transport.
Cyclic strain also induced the release of transforming growth factor-beta1 in a
time- and strain-dependent manner. Moreover, conditioned media from SMCs exposed
to cyclic strain stimulated the transport of L-proline in control, static SMCs
and this was significantly attenuated by a transforming growth factor-beta1
neutralizing antibody. CONCLUSIONS: These results demonstrate that cyclic strain
stimulates L-proline transport by inducing system A amino acid transporter 2
gene expression through the autocrine release of transforming growth
factor-beta1. The ability of cyclic strain to induce system A amino acid
transporter 2 expression may promote arterial remodeling in hypertension by
providing vascular SMCs with the necessary intracellular levels of L-proline
required for collagen synthesis and cell growth. Copyright 2004 American Journal
of Hypertension, Ltd.

PMID: 15288886 [PubMed - indexed for MEDLINE]