Agonist-induced isotonic contraction of cultured mesangial cells after multiple passage

Contractile cells under conditions of prolonged culture lose their ability to contract in the usual manner (i.e., isotonically). One explanation for this may be that contraction is prevented by tight cell-to-substrate adhesion. Two models in which substrate adhesiveness was expected to be diminished were used to test this hypothesis. In one, cells were seeded onto collagen-coated dishes and used within 40 min of plating. In the other, cells were plated onto dishes coated with poly-2-hydroxyethyl methacrylate (poly-HEMA) and used, depending on thickness of the poly-HEMA substrate, up to periods of 1 wk. Cells plated onto such substrates contracted when challenged with either PGE2 (2 X 10(-6) and 2 X 10(-9) M), arginine vasopressin (AVP, 10(-6)-10(-9) ), or the calcium ionophore A23187 (5 micrograms/ml). Contraction took place within 5-15 min at 37 degrees C. The contraction seen with AVP was due to its pressor action because 1-desamino-8-D-arginine vasopressin (dDAVP), the antidiuretic analogue, did not cause contraction and the anti-pressor analogue [1-(beta-mercapto-beta beta-cyclopentamethylene propionic acid)-4-valine 8-D-arginine]-vasopressin [d(CH2)5-VDAVP] blocked contraction by AVP. The contraction seen with AVP was dependent on extracellular calcium, whereas that observed with prostaglandin E2 (PGE2) was not.(ABSTRACT TRUNCATED AT 250 WORDS)