Toxicity of fatty acid 18:5n3 from Gymnodinium cf. mikimotoi: I. Morphological and biochemical aspects on Dicentrarchus labrax gills and intestine.

We present evidence for the toxic effects of fatty acid 18:5n3 (octadecapentaenoic acid) in the gills and intestine of the sea bass Dicentrarchus labrax. Light microscopic observation of gills showed strong mucus production and alteration of ionocytes. The Mg- and Na,K-ATPase activities were inhibited, with IC50 values of 10(-3) and 1.

Toxicity of fatty acid 18:5n3 from Gymnodinium cf. mikimotoi: II. Intracellular pH and K+ uptake in isolated trout hepatocytes.

Effects of octadecapentaenoic acid 18:5n3 and other related polyunsaturated fatty acids present in gymnodinium cf. mikimotoi were tested in isolated trout hepatocytes. These exotoxins decreased intracellular pH followed by a slow recovery to initial value and alkalinization of acidic compartments, suggesting an inhibition of vacuolar H(+)-ATPases.

Na+/H+ exchange and osmotic shrinkage in isolated trout hepatocytes.

The ability of rainbow trout liver cells to regulate their intracellular pH (pHi) was studied using two methods on hepatocytes isolated by collagenase digestion: (i) by monitoring pHi with the fluorescent dye BCECF-AM, and (ii) by measuring the amiloride-sensitive uptake of 22Na, which represents Na+/H+ exchange. In low-Na+ medium (¾16mmoll-1), Na+ uptake was reduced by approximately 70% in the presence of amiloride derivatives (DMA or MPA, 10(-4)moll-1). Changing separately either the extracellular pH (pHe) or the intracellular pH (pHi, clamped by treating the cells with nigericin in the presence of 140mmoll-1 K+) between 6 and 8 induced an increase in the rate of Na+ uptake when pHe was raised or when pHi was reduced.

Effect of caulerpenyne, a toxin extracted from Caulerpa taxifolia on mechanisms regulating intracellular pH in sea urchin eggs and sea bream hepatocytes.

The proliferation of the green marine alga Caulerpa taxifolia in the Mediterranean led us to investigate the toxic effects on marine organisms of caulerpenyne (Cyn), the major secondary metabolite synthesized by the alga. This study was performed on sea urchin eggs (Paracentrotus lividus) and isolated hepatocytes from the sea bream (Sparus aurata), in which accumulation of the toxins by metabolic processes may be of significance. Cyn provoked an acidification of seawater containing both unfertilized and fertilized eggs, as revealed by a titrable efflux of protons.

Potassium uptake and water content in hepatocytes isolated from rat livers preserved in Euro-Collins and UW solutions and after transplantation.

Isolated hepatocytes from the rat were used to assess the maintenance of liver cell function in relation to the composition of the preservation medium. After separation by collagenase, they were incubated in Krebs-Ringer-Bicarbonate medium (KRB), Euro-Collins (EC), or University of Wisconsin (UW) solutions. Potassium influx, cell volume, and transaminase release were measured in cells freshly separated from control livers or from livers preserved in vitro up to 12 h in these media or having undergone orthotopic liver transplantation (OLT).