May 10th, 2020

savanna life


Меня если торкнет, то...ну,  вы знаете:)

In our experiments, blood incubation with NO donors (glyceryltrinitrate, molsidomine, sodium nitroprusside, S-nitrosocysteine) or NO-synthase substrate (L-arginine) did not change HOA even at NO:Hb ratio of 1:1. At the same time our results showed that oxygenated blood incubation with S-nitrosocysteine induced an oxyhemoglobin dissociation curve shift leftwards. This indicates a leading role of met-Hb in a modification of Hb oxygen-binding properties. However other NO-modified forms of hemoglobin (S-nitroso- and nitrosylhemoglobin) also may be involved in the regulation of HOA. The results obtained indicate that nitric oxide can be the allosteric effector of hemoglobin, increasing or decreasing its oxygen affinity - possibly, through the generation of different NO-Hb derivatives.

Отсюда, (если гипотеза верна), вытекает и разнообразие реакций пациентов на ковид.
Какие derivatives, такие и реакции.

Research has shown the importance of compartmentalization of Hb in the red cell in limiting the destruction of NO by Hb. In addition oxidation of Hb to form metHb reduces the ability of Hb to sequester or destroy NO. A Hb oxidation-reduction mechanism was recently proposed to control NO signaling in myoendothelial junctions. This function of alphahemoglobin in NO signaling may be present in other cell types as alphaHb is found in many cells and its function is not fully understood.
The role of Hb in the vasodilatory role of nitrite is also not fully understood. DeoxyHb can act as a nitrite reductase to produce NO; however, NO produced by Hb in the RBC would then be subject to interactions with other deoxygenated and oxygenated hemoglobins. Formation of N2O3 or S-nitrosthiols from the Hb/nitrite reaction may be the key to nitrite-mediated NO activity export from red blood cells, but the mechanism remains a matter of debate. It is clear that Hb plays a significant role in NO signaling; however, many questions remain surrounding the precise mechanisms of NO activity preservation as well as if and how Hb creates NO activity, making Hb NO research an exciting area for future research.

А вот это просто исключительно интересно - вы знали, что эндотелиальные клетки вырабатывают гемоглобин у людей (и мышей) с легочной артериальной гипертензией? Ее симптомами (в том числе) являются разрушение мелких сосудов и тромбоз.
Вирус вяжется к ангиотензивному рецептору эндотелия альвеол. Какая-то связь тут, возможно, что и есть.

Alvarez and colleagues (pp. 733–744) show that hemoglobin α (Hb α) is expressed in pulmonary endothelium from humans and mice with PAH (3). Normally, Hb α is expressed as a heterodimer with Hb β in the erythrocyte; however, an increasing number of studies have observed expression of Hb in nonerythroid cells (4). Alvarez and colleagues provide evidence that increased Hb α in pulmonary ECs is responsible for decreased NO bioavailability and impaired responses to vasodilatory stimuli, including bradykinin and acetylcholine, both of which are canonical stimulators of eNOS activation. Interestingly, they were able to restore a vasodilatory response to acetylcholine by disrupting the interaction between Hb α and eNOS in the endothelium, using an Hb α mimetic peptide.

И из свежего, очень понятный и хороший обзор, к сожалению, полным доступом этого для всех нет, но где искать хаб, вы знаете)