The positive inotropic effect of endothelin-1 is mediated by mitochondrial reactive oxygen species.

We have previously demonstrated the participation of reactive oxygen species (ROS) in the positive inotropic effect of a physiological concentration of Angiotensin II (Ang II, 1 nM). The objective of the present work was to evaluate the role and source of ROS generation in the positive inotropic effect produced by an equipotent concentration of endothelin-1 (ET-1, 0.4 nM). Isolated cat ventricular myocytes were used to measure sarcomere shortening with a video-camera, superoxide anion (()O(2)(-)) with chemiluminescence, and ROS production and intracellular pH (pH(i)) with epifluorescence. The ET-1-induced positive inotropic effect (40.4+/-3.1%, n=10, p<0.05) was associated to an increase in ROS production (105+/-29 fluorescence units above control, n=6, p<0.05). ET-1 also induced an increase in ()O(2)(-) production that was inhibited by the NADPH oxidase blocker, apocynin, and by the blockers of mitochondrial ATP-sensitive K(+) channels (mK(ATP)), glibenclamide and 5 hydroxydecanoic acid. The ET-1-induced positive inotropic effect was inhibited by apocynin (0.3 mM; 6.3+/-6.6%, n=13), glibenclamide (50 microM; 8.8+/-3.5%, n=6), 5 hydroxydecanoic acid (500 microM; 14.1+/-8.1, n=9), and by scavenging ROS with MPG (2 mM; 0.92+/-5.6%, n=8). ET-1 enhanced proton efflux (J(H)) carried by the Na(+)/H(+) exchanger (NHE) after an acid load, effect that was blocked by MPG. Consistently, the ET-induced positive inotropic effect was also inhibited by the NHE selective blocker HOE642 (5 microM; 9.37+/-6.07%, n=7). The data show that the effect of a concentration of ET-1 that induces an increase in contractility of about 40% is totally mediated by an intracellular pathway triggered by mitochondrial ROS formation and stimulation of the NHE.

Modulation of streptonigrin's clastogenic effects in CHO cells by the metal-chelating agent 1,10-phenanthroline.

The effect of the metal-chelating agent 1,10-phenanthroline (PNT) on the clastogenesis induced by streptonigrin (SN) in CHO cells was investigated. When CHO cells were exposed to SN, chromosomal aberrations (CAs) and sister-chromatid exchanges (SCEs) were formed in a dose-dependent manner (P < 0.05). When PNT was present in the culture medium, the production of CAs by SN was strongly inhibited (inhibition range = 54.9-80.8%). Similarly, the induction of SCEs by SN was significantly decreased by the addition of PNT to CHO cultures (P < 0.05), although the effect was minor. This finding suggests that intracellular transition metals are implicated in the clastogenesis by SN, and that the Fenton reaction (Fe(2+) + H2O2 --> OH* + OH(-) + Fe(3+)) may be responsible for the production of CAs by this compound. Moreover, the fact that PNT did not completely inhibit the induction of SCEs by SN suggests that this phenomenon might be attributable to a different mechanism, in which transition metals and free radicals play a minor role.

[New reproductive technologies: oocyte donation. What could be new in this field?]. / Novas tecnologias reprodutivas: doação de óvulos. O que pode ser novo nesse campo?

This article discusses the so-called "new" reproductive technologies. The author analyzes and challenges this adjective, since for over two decades this group of medical techniques and experiments has been widely disseminated in the medical market. The media's coverage of test tube babies, and especially developments in intervention on human germ cells and embryos, help challenge the supposed permanent novelty of everything surrounding reproductive technologies and genetic interventions. Society is doubtless experiencing an open process in full innovation, but the social and symbolic effects on planning maternity, paternity, and filiation are still not well perceived or discussed. To illustrate such contradictions, the article focuses on the case of oocyte donation, highlighting the need for new perspectives in terms of social control over the dissemination of reproductive technologies.