Diphenylhydantoin effects on salivary secretion and microsomal calcium accumulation and release

Effect of calcium-channel blockers on cell proliferation, DNA synthesis and collagen synthesis of cultured gingival fibroblasts derived from human nifedipine responders and non-responders

Human gingival fibroblasts from six patients who developed gingival hyperplasia as a result of nifedipine medication and five who did not were studied for the effects of calcium-channel blockers (nifedipine, diltiazem, verapamil and nicardipine) on cell proliferation, DNA synthesis and collagen synthesis. Phenytoin was used as a positive control. The fibroblasts from reactive patients gave trends toward better cell proliferation rates, DNA synthesis ([3H]-thymidine incorporation), and collagen synthesis ([3H]-proline incorporation) than those from non-reactive patients in the presence of 1 microM of calcium-channel blockers or phenytoin.

Diphenylhydantoin: effects on amylase release, cyclic nucleotides and ion fluxes in mouse parotid acini

The effects of diphenylhydantoin were investigated on isolated mouse parotid acini. Diphenylhydantoin inhibited carbachol-stimulated amylase release at concentrations of 5 X 10(-4) M and greater; isoproterenol-stimulated amylase release was not affected. The inhibition of carbachol-stimulated amylase release was attributable to inhibition of 45Ca2+ uptake. The ability of diphenylhydantoin to inhibit carbachol-stimulated cyclic GMP (c-GMP) accumulation was also related to inhibition of 45Ca2+ uptake. Diphenylhydantoin (5 X 10(-4)M) alone, was found to stimulate c-GMP accumulation, an effect related to enhanced 45Ca2+ efflux. Diphenylhydantoin alone, however, failed to enhance amylase release. These findings suggest that the effects of diphenylhydantoin on carbachol-stimulated amylase release and on c-GMP accumulation are related to its effects on transmembrane calcium movements.

Effects of ionophores A23187 and X537A on vascular smooth muscle activity

The ionophore A23187 initiated contractions in both dog coronary artery and rabbit aortic strips in a dose-dependent manner whereas X537A contracted rabbit aortic strips and relaxed KCl-induced contractions in dog coronary artery. Diphenylhydantoin (DPH) and verapamil ccompletely abolished KCl-induced responses in both vascular tissues. DPH (10(-4) M) partially prevented A23187-induced responses in both tissues and verapamil (33 micrometer) partially prevented A23187-induced responses in dog coronary artery but not in rabbit aorta. Phenoxybenzamine (10(-5) M), but not practolol, significantly reduced X537A-induced contractions in rabbit aortic strips but did not affect A23187-induced contractions in either tissue. The inability of DPH and verapamil to completely block the A23187 contractions leads one to conclude that these agents do not completely block calcium influx, or that A23187 does not work solely by increasing the permeability of the cell membrane to calcium. The effect of X537A on rabbit aorta, however, may be mediated at least partially, via release of catecholamines.