Ufnal, M. | Search bioRxiv

bioRxiv2021

Methane, a gut bacteria-produced gas, does not affect arterial blood pressure in normotensive anaesthetized rats.

Methane is produced by carbohydrate fermentation in the gastrointestinal tract through the metabolism of methanogenic microbiota. Several lines of evidence suggest that methane exerts anti-inflammatory, anti-apoptotic and anti-oxidative effects. The effect of methane on cardiovascular system is obscure. The objective of the present study was to evaluate the hemodynamic response to methane. A vehicle or methane-rich saline were administered intravenously or intraperitoneally in normotensive anaesthetized rats. We have found no significant effect of the acute administration of methane-rich saline on arterial blood pressure and heart rate in anaesthetized rats. Our study suggests that methane does not influence the control of arterial blood pressure. However, further chronic studies may be needed to fully understand hemodynamic effects of the gas.

physiology↗

bioRxiv2020

TMAO, a seafood-derived molecule, produces diuresis and reduces mortality in heart failure rats

BackgroundThere is an ongoing debate whether trimethylamine-oxide (TMAO), a molecule present in seafood and a derivate of microbiota metabolism, is beneficial or harmful for the circulatory system. Interestingly, deep-water animals accumulate TMAO that protects proteins such as lactate dehydrogenase (LDH) against high hydrostatic pressure. We hypothesized that TMAO may benefit the circulatory system by protecting cardiac LDH exposed to hydrostatic stress (HS) produced by contracting heart. Methods and ResultsMale, 6-week-old, Sprague-Dawley (SD, n=40) and Spontaneously-Hypertensive-Heart-Failure (SHHF n=18) rats were divided into either Water or TMAO oral treatment. After 56 weeks, half of Water and TMAO SD rats were given isoprenaline (ISO) to produce catecholamine stress. In vitro, LDH with or without TMAO was exposed to HS (changes in pressure 0-250mmHg x 280min-1) and was evaluated using fluorescence correlation spectroscopy. After 58 weeks of the treatment survival was 100% in SD-Water, SD-TMAO, ISO-TMAO and 90% in ISO-Water. In SHHF-Water survival was 66% vs 100% in SHHF-TMAO. In general, TMAO-treated rats showed higher diuresis and natriuresis. In comparison to SHHF-Water, SHHF-TMAO showed significantly lower diastolic arterial blood pressure, plasma NT-proBNP and expression of angiotensinogen and AT1 receptors in the heart. In separate experiments, intravenous TMAO but not vehicle or urea significantly increased diuresis in SD. In vitro, exposure of LDH to HS with or without TMAO did not affect the protein structure. ConclusionsTMAO reduces mortality in SHHF rats that is associated with diuretic, natriuretic and hypotensive effects. HS produced by the contracting heart is neutral for cardiac LDH structure.

physiology↗