Expression of receptor for advanced glycosylation end products (AGEP) and inhibition of AGEP-induced cytosolic calcium elevation by diltiazem in cultured rat aortic smooth muscle cells
Abstract
AIM: To study whether there is a high affinity receptor for advanced
glycosylation end product (AGEP) on thoracic aorta smooth muscle cells (ASMC) and
to test effect of diltiazem on elevation of cytosolic free calcium induced by
AGEP.
METHODS: Interactions of AGEP-bovine serum albumin (BSA) with ASMC were studied
with radioligand binding assay and cytosolic free calcium ([Ca2+]i) was examined
in cultured ASMC with Fura 2-AM.
RESULTS: AGEP-BSA was specifically bound to cells at 4 degrees C and was taken up
and degraded at 37 degrees C. These processes were concentration-dependent and
saturable. Scatchard analysis indicated that the receptor was with dissociation
constant of 65.3 +/- 1.5 nmol.L-1 and its maximal binding capacity of 1.57 +/-
0.04 nmol/g cell protein. Early glycated low density lipoprotein (LDL) was not
recognized by this receptor. AGEP-BSA elevated cytosolic free calcium in a
concentration-dependent manner. Pretreatment with diltiazem inhibited
AGEP-BSA-induced elevation in concentration- and time-dependent manners.
CONCLUSION: There was a high affinity receptor for AGEP on ASMC, which mediated
internalization and degradation of AGEP. Pretreatment with diltiazem inhibited
the AGEP-induced elevation of cytosolic free calcium.
Keywords:
glycosylation end product (AGEP) on thoracic aorta smooth muscle cells (ASMC) and
to test effect of diltiazem on elevation of cytosolic free calcium induced by
AGEP.
METHODS: Interactions of AGEP-bovine serum albumin (BSA) with ASMC were studied
with radioligand binding assay and cytosolic free calcium ([Ca2+]i) was examined
in cultured ASMC with Fura 2-AM.
RESULTS: AGEP-BSA was specifically bound to cells at 4 degrees C and was taken up
and degraded at 37 degrees C. These processes were concentration-dependent and
saturable. Scatchard analysis indicated that the receptor was with dissociation
constant of 65.3 +/- 1.5 nmol.L-1 and its maximal binding capacity of 1.57 +/-
0.04 nmol/g cell protein. Early glycated low density lipoprotein (LDL) was not
recognized by this receptor. AGEP-BSA elevated cytosolic free calcium in a
concentration-dependent manner. Pretreatment with diltiazem inhibited
AGEP-BSA-induced elevation in concentration- and time-dependent manners.
CONCLUSION: There was a high affinity receptor for AGEP on ASMC, which mediated
internalization and degradation of AGEP. Pretreatment with diltiazem inhibited
the AGEP-induced elevation of cytosolic free calcium.