Comparisons of Blood Parameters, Red Blood Cell Deformability and Circulating Nitric Oxide Between Males and Females Considering Hormonal Contraception: A Longitudinal Gender Study

Abstract

Red blood cell (RBC) deformability is an important determinant of the microcirculation. It is influenced by various hematological parameters but also by nitric oxide (NO) which is produced in RBC from L-arginine by RBC-NO synthase. Longitudinal studies on blood profile, deformability at rest and NO levels but also differences between males and females (±hormonal contraception; HC) are less known so far. The study thus aimed to investigate RBC deformability, RBC NO species (nitrite, RxNO), RBC L-arginine concentration and basal blood parameters in males and females (±HC) as a function of time. RBC deformability was measured at rest once per week and the remaining parameters were measured once per month, respectively. A second experiment aimed to daily measure RBC deformability and 17β-estradiol in Female ± HC during a whole menstruation cycle to investigate a possible relation of the two parameters. Measured parameters showed low week-to-week variation and remained constant during study period. However, RBC deformability increased in Female + HC during study period possibly because of increasing training volume of the participants. Overall, results indicate gender differences in hematological parameters with higher RBC parameters (RBC count, hematocrit, hemoglobin concentration) in males compared to females. Differences were also observed between the female groups with Females - HC showing lower number of RBC but higher MCV and hematocrit compared to Females + HC. RBC deformability was highest in Females - HC which might be related to permanent higher estradiol levels and/or higher RBC NO levels because RBC nitrite and RBC RxNO concentrations were also highest in Females-HC. Results of the second experiment also suggest higher RBC deformability in Female - HC because of higher estradiol concentrations. L-arginine levels known to be related to RBC NO production were comparable in all groups. In conclusion, hematological, hemorheological and NO related parameters show gender differences. In particular, RBC deformability is affected by training volume and RBC estradiol concentrations. The results add new information on the complex regulation of RBC function which might help to better understand the role of RBC in the microcirculation.

Impact of Trail Running Races on Blood Viscosity and Its Determinants: Effects of Distance

“…The relatively small sample size of our study did not allow us to evaluate the impact of sex on the different parameters analyzed. Previous studies have reported sex differences in hematological parameters with higher RBC count, hematocrit, and hemoglobin concentration in males than in females [ 40 , 41 ]. Grau et al [ 40 ] also described that RBC deformability was higher in females not taking hormonal contraception (HC) compared to women taking hormonal contraception and compared to males.…”

“…Previous studies have reported sex differences in hematological parameters with higher RBC count, hematocrit, and hemoglobin concentration in males than in females [ 40 , 41 ]. Grau et al [ 40 ] also described that RBC deformability was higher in females not taking hormonal contraception (HC) compared to women taking hormonal contraception and compared to males. Further studies are needed to test the sex differences on the hematological and RBC responses during such long-distance races.…”

The march in place activity – a view from the local concentration of red blood cells (CRBC) in the human foot dorsum

“…Na posição em pé, a ausência de mecanismos reguladores permitiria o preenchimento dos vasos dos pés entre 300 e 800 ml, correspondendo ao deslocamento gravitacional do sangue, de modo que, em indivíduos saudáveis, esse é um fenômeno preventivo [20]. investigation comparing blood red cell passage values in the upper limb antecubital region, the authors identified higher values for men compared with women [26]. However, other studies on microcirculation did not find differences between genders [27], so further studies seem to be necessary to compare responses among healthy individuals with different physiological characteristics.…”

“…The authors declare that there is no financial or personal relationship that might be perceived as posing a potential conflict of interest [26]. No entanto, outros estudos sobre a microcirculação não encontraram diferenças entre os gêneros [27], portanto, estudos adicionais parecem ser necessários para comparar as respostas entre indivíduos saudáveis com diferentes características fisiológicas.…”

Old cells die hard – sympatholysis and the ageing erythrocyte

“…While reduced deformability appears to be characteristic of healthy ageing, changes in circulating sex hormones in young versus post-menopausal women may be critical to erythrocyte function. Grau et al (2018) recently investigated the effects of fluctuating plasma oestrogen levels across the menstrual cycle on various haematological factors, including erythrocyte deformability. They present novel evidence that circulating oestrogen enhances erythrocyte deformability.…”