Inhibition of pinocytosis in rat yolk sac by trypan blue

Abstract

Day 17.5 yolk sacs from rats injected with partially denatured 125I-labeled bovine serum albumin (I-BSA) were cultured in vitro by a raft technique. The rates of release of [125I]iodotyrosine were similar in control yolk sacs and in yolk sacs from rats preinjected with trypan blue. Day 17.5 rat yolk sacs were also cultured in medium containing I-BSA. Following pinocytic uptake the substrate was degraded intracellularly and [135I]iodotyrosine released into the medium. Trypan blue, when present in the medium in concentrations above 100 mug/ml, inhibited pinocytosis of I-BSA and so decreased the rate of [125I]iodotyrosine production. Trypan blue similarly decreased the rate of pinocytic uptake of 125I-labeled polyvinylpyrrolidone. Pinocytic uptake of macromolecules was not decreased in yolk sacs from rats pretreated with trypan blue. The relevance of these results to the mechanism of teratogenic action of trypan blue is discussed. It is proposed that if trypan blue in teratogenic doses similarly inhibits pinocytosis by the yolk sac during the organogenetic period teratogenesis might result from a transient interruption in the flow of metabolites through the yolk sac to the embryo.

Whole protein uptake and metabolism by mouse blastocysts

“…The results (Fig. 4) show that for both (Williams, Roberts, Kidston, Beck & Lloyd, 1976;Field et al, 1977). Preliminary tests showed that the dye did not affect the development of embryos in vitro.…”

“…This conclusion is supported by the electron microscopic studies of rat (Schlafke & Enders, 1973) and rabbit (Hastings & Enders, 1974) preimplantation embryos which show exogenous proteins in pinocytotic vesicles and bound to the membrane. Uptake was reversibly inhibited by trypan blue which has been described as a specific reversible inhibitor of pinocytosis (Williams et al, 1976;Field et al, 1977).…”

Possible mechanism of gene transfer into early to mid-gestational mouse fetuses by tail vein injection

“…27,28 Since TB possibly does not go beyond the VE, we further examined whether fluorescence-labeled DNA/lipid complexes exhibit a distribution similar to that of TB. Fluorescence-labeled HaeIII-digested pBluescript SK(Ϫ) plasmid vector fragments were column-purified (Figure 6a) and mixed with FuGENE6.…”

N-(2-Hydroxypropyl)methacrylamide copolymers targeted to the hepatocyte galactose-receptor: pharmacokinetics in DBA2 mice

“…distribution governed mainly by molecular weight-dependent extravasation and glomerular filtration (Seymour et al, 1987). Their slow accumulation by cells is via fluid-phase pinocytosis (Duncan et al, 1981), an uptake mechanism which is not saturable and where the amount of material captured is directly proportional to its concentration in the extracellular fluid (Williams et al, 1975a). In contrast, copolymers containing targeting residues (e.g.…”

“…Conjugate 2) can also enter target cells by receptor-mediated pinocytosis. This process involves the substrate binding to specific receptors on the plasma membrane and constitutes an efficient method of uptake at low substrate concentrations, although it typically shows receptor-saturation at high concentrations (Williams et al, 1975b).…”