CD36 Deficiency Leads to Choroidal Involution via COX2 Down-Regulation in Rodents

Florian Sennelaub and colleagues show that CD36 deficiency leads to choroidal involution, a key feature of "dry" age-related macular degeneration, via COX-2 down-regulation in the retinal pigment epithelium

Hydrogen sulfide in the mouse ductus arteriosus: a naturally occurring relaxant with potential EDHF function

We have previously reported that bradykinin relaxes the fetal ductus arteriosus via endothelium-derived hyperpolarizing factor (EDHF) when other naturally occurring relaxants (prostaglandin E(2), nitric oxide, carbon monoxide) are suppressed, but the identity of the agent could not be ascertained. Here, we have examined in the mouse whether hydrogen sulfide (H(2)S) is a relaxant of the ductus and, if so, whether it may also function as an EDHF. We found in the vessel transcripts for the H(2)S synthetic enzymes, cystathionine-\u3b3-lyase (CSE) and cystathionine-\u3b2-synthase (CBS), and the presence of these enzymes was confirmed by immunofluorescence microscopy. CSE and CBS were distributed across the vessel wall with the former prevailing in the intimal layer. Both enzymes occurred within the endoplasmic reticulum of endothelial and muscle cells, while only CSE was located also in the plasma membrane. The isolated ductus contracted to inhibitors of CSE (D,L-propargylglycine, PGG) and CBS (amino-oxyacetic acid, AOAA), and PGG contraction was attenuated by removal of the endothelium. EDHF-mediated bradykinin relaxation was curtailed by both PGG and AOAA, while the relaxation to sodium nitroprusside was not affected by either treatment. The H2S donor, sodium hydrogen sulfide (NaHS), was also a potent, concentration-dependent relaxant. We conclude that the ductus is endowed with a H(2)S system exerting a tonic relaxation. In addition, H(2)S, possibly via an overriding CSE source, qualifies as an EDHF. These findings introduce a novel vasoregulatory mechanism into the ductus, with implications for antenatal patency of the vessel and its transitional adjustments at birth