Extracellular ATP potentiates steroidogenic effect of adrenocorticotropic hormone in bovine adrenocortical fasciculata cells.

We examined the effect of extracellular adenosine 5'-triphosphate (ATP) on adrenocorticotropic hormone (ACTH)- and angiotensin II-induced steroidogenesis in bovine adrenocortical fasciculata cells. The low concentration of ATP (5 microM) potentiated ACTH-induced steroidogenesis synergistically. However, the purine derivative did not affect angiotensin II-induced steroidogenesis. Although adenosine (100 microM) (a metabolite of ATP) showed a weak steroidogenic effect, it did not potentiate ACTH-induced steroidogenesis. ATP also enhanced the steroidogenesis by NaF synergistically in bovine adrenocortical cells, but did not potentiate forskolin- and dibutyryl cyclic AMP-induced steroidogenesis. The stimulating effect of ACTH on cyclic AMP production was synergistically accelerated by ATP (5 microM), which has no effect by itself on cyclic AMP formation. These results suggest that extracellular ATP affected the ACTH receptor-adenylyl cyclase coupling processes, and potentiation of steroidogenesis by ACTH ensued in bovine adrenocortical fasciculata cells.

Evaluation of antifungal activity of an antifungal drug by in vitro simulation of in vivo pharmacokinetics of the drug against fungal hyphal growth.

An automatic drug concentration simulator (DCS) has been developed and its applicability has been demonstrated by in vitro simulation of the human plasma concentration-time curve of fluconazole (FLCZ) against hyphal growth of Candida albicans and Aspergillus fumigatus. The response of hyphal growth to FLCZ was continually monitored and analyzed using an automatic hyphal growth analyzing system (Bio-Cell Tracer). The simulated concentration of FLCZ by DCS was confirmed by HPLC. The DCS assay was reproducible with a mean coefficient of variation (C.V., n=3) of 5.38 %. When the growth of C. albicans hyphae was tested, there was a lag of onset of FLCZ effect between the time when FLCZ concentration became maximal (C MAX, 7.95 microg/ml ) and the point at which hyphal growth ceased. In contrast, FLCZ was found inactive against A. fumigatus. The newly devised technique could provide clinicians with important information in determining optimal dosing regimens for antifungal drugs.

[The influence of the alcohol and the low protein diet on rat pancreas].

We investigated the influence of alcohol and the low protein diet upon rat pancreas. Rats were separated in four groups, 1) Control diet group (Cont), 2) Alcohol diet group (Al), 3) Low protein diet group (Lp), 4) Low protein and alcohol diet group (Lp+Al). They were fed on isocaloric liquid diet compulsorily through the gastric tube. They were sacrificed 3, 6, 12 weeks after. By the light microscopic observation on the rat pancreas which were fed for 12 weeks, lipid droplets in the acinar cells were observed in all groups other than Cont. Apoptosis was founded in Lp and Lp+Al groups. Protein plugs were observed in all groups, and no relation was found between the plugs and the location of the injured acinar cells. By the electromicroscopic observation, in Lp+Al group, acinar cells were typically injured (ER dilation, atrophic nuclei, mitochondria degeneration, etc.) and mesenchymal cells appeared among acinar cells. These results suggest that alcohol causes pancreatic acinar cell injury directly, and relative low protein diet helps to turn it worse.

Calcium is essential for ATP-induced steroidogenesis in bovine adrenocortical fasciculata cells.

The effect of extracellular ATP on steroidogenesis in primary cultured bovine adrenocortical fasciculata cells was investigated. I observed that in the presence of extracellular Ca2+, ATP caused a dose-dependent elevation of intracellular Ca2+ ([Ca2+]i) and induced steroidogenesis concentration- and time-dependently. However, in the absence of extracellular Ca2+, ATP had no effect on steroidogenesis. In the presence of extracellular Ca2+, calmodulin inhibitors inhibited the ATP-induced steroidogenesis, but dihydropyridine calcium channel blockers did not. Furthermore, ATP did not cause an elevation of cyclic AMP in bovine adrenocortical fasciculata cells even if extracellular Ca2+ existed. These results suggest that extracellular ATP might have an influence on bovine adrenocortical cells via the purinoceptor (P2Y) in connection with calcium mobilization, open the non-selective calcium channel and induce steroidogenesis by means of an elevation of [Ca2+]i via the calcium-calmodulin system.

Extracellular ATP stimulates steroidogenesis in bovine adrenocortical fasciculata cells via P2 purinoceptors.

Effects of ATP and other purine derivatives on steroidogenesis in primary cultured bovine adrenocortical fasciculata cells were examined. At concentrations higher than 1 microM, ATP showed a potent stimulative effect on the cortisol production of the cells. The potency order of the steroidogenic effect of the tested purine derivatives was ATP greater than ADP much greater than adenosine much greater than AMP. alpha,beta-Methylene ATP had no stimulative effect on the steroidogenesis at concentrations as high as 1 mM. Theophylline did not antagonize the steroidogenic effect of ATP. These results suggest that bovine adrenocortical fasciculata cells possess the P2y purinoceptors that are linked to steroidogenesis.