ABSTRACT
Mebudipine and dibudipine are two newly synthesized dihydropyridine (DHP) calcium channel blockers that have been shown to have considerable relaxant effects on vascular and atrial smooth muscle. The in vitro half-lives of mebudipine and dibudipine are reported to be significantly longer than that of nifedipine. In this study, we investigated the effects of mebudipine and dibudipine on voltage-activated Ca2+ channels on differentiated PC12 cells and compared their potencies to amlodipine. Our results point to absence of voltage-activated Ca2+ currents in undifferentiated PC12 cells. It is also concluded that mebudipine and dibudipine, like amlodipine are L-type calcium channel blockers. When tested in a range of 10-100 microM, mebudipine is at least as potent as amlodipine in inhibition of peak Ba2+ currents in differentiated PC12 cells while dibudipine is significantly less potent compared to amlodipine and mebudipine.
Subject(s)
Calcium Channel Blockers/pharmacology , Calcium Channels, L-Type/drug effects , Neurons/drug effects , Nifedipine/analogs & derivatives , Amlodipine/pharmacology , Animals , Barium Compounds/metabolism , Calcium Channels, L-Type/metabolism , Cell Differentiation , Chlorides/metabolism , Dose-Response Relationship, Drug , Membrane Potentials/drug effects , Nerve Growth Factor/metabolism , Neurons/metabolism , Nifedipine/pharmacology , PC12 Cells , RatsABSTRACT
Cryopreserved sperm exhibit lower fertilizing capacity in comparison to fresh sperm, partly due to effects of glycerol as the common cryoprotectant medium. Since standard semen analysis is not a good predictive method to assess sperm fertilizing capacity, functional tests like cervical mucus penetration may provide more useful information. A total of 24 semen samples were examined before and after cryopreservation for sperm parameters as well as number and motility of penetrated sperm into bovine cervical mucus (BCM) as an alternative for human cervical mucus. Freezing and thawing procedures have negative effects on sperm penetration into cervical mucus. No significant relation was noticed between sperm motility percentage or its penetration into BCM before and after cryopreservation, which denotes the variability in resistance of sperm to damaging effects of freezing.
