Discrepancy Between Bioavailability and Hypotensive Effect of Oral and Sublingual Nifedipine

Palma-Aguirre, José Antonio; Montoya-Cabrera, M A; Souich, P. du; Hoyo‐Vadillo, Carlos; Flores‐Murrieta, Francisco J.; Castañeda‐Hernández, Gilberto

doi:10.1097/00045391-199501000-00002

Cited by 1 publication

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“…It is also possible that by inhibiting IP formation, DHPs produce feedback effects on NT binding. Given that DHPs altered NTR1 function at concentrations near to the blood levels (ϳ0.2 M) in patients receiving these drugs therapeutically (Palma-Aguirre et al, 1995) and below those used for in vitro work (Lopez et al, 1993;Triggle, 2003), these effects could be of clinical and pharmacological importance.…”

Section: Discussionmentioning

confidence: 99%

Polyphenolic Antioxidants Mimic the Effects of 1,4-Dihydropyridines on Neurotensin Receptor Function in PC3 Cells

Carraway

Hassan²,

Cochrane³

2004

J Pharmacol Exp Ther

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This study aimed to determine the mechanism(s) by which 1,4-dihydropyridine Ca 2ϩ channel blockers (DHPs) enhance the binding of neurotensin (NT) to prostate cancer PC3 cells and inhibit NT-induced inositol phosphate formation. Earlier work indicated that these effects, which involved the G proteincoupled NT receptor NTR1, were indirect and required cellular metabolism or architecture. At the micromolar concentrations used, DHPs can block voltage-sensitive and store-operated Ca 2ϩ channels, K ϩ channels, and Na ϩ channels, and can inhibit lipid peroxidation. and [Na ϩ ], we showed that these ions did not contribute to either effect. For a series of DHPs, the activity order for effects on NTR1 function followed that for antioxidant ability. Antioxidant polyphenols (luteolin and resveratrol) mimicked the effects of DHPs and showed structural similarity to DHPs. Antioxidants with equal redox ability, but without structural similarity to DHPs (such as ␣-tocopherol, riboflavin, and N-acetyl-cysteine) were without effect. A flavoprotein oxidase inhibitor (diphenylene iodonium) and a hydroxy radical scavenger (butylated hydroxy anisole) also displayed the effects of DHPs. In conclusion, DHPs indirectly alter NTR1 function in live cells by a mechanism that depends on the drug's ability to donate hydrogen but does not simply involve sulfhydryl reduction.

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Section: Discussionmentioning

confidence: 99%