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Sex as a biological variable for cardiovascular physiology

There have been ongoing efforts by federal agencies and scientific communities since the early 1990s to incorporate sex and/or gender in all aspects of cardiovascular research. Scientific journals provide a critical function as change agents to influence transformation by encouraging submissions for topic areas, and by setting standards and expectations for articles submitted to the journal. As part of ongoing efforts to advance sex and gender in cardiovascular physiology research, the American Journal of Physiology-Heart and Circulatory Physiology recently launched a call for papers on Considering Sex as a Biological Variable. This call was an overwhelming success, resulting in 78 articles published in this collection. This review summarizes the major themes of the collection, including Sex as a Biological Variable Within: Endothelial Cell and Vascular Physiology, Cardiovascular Immunity and Inflammation, Metabolism and Mitochondrial Energy, Extracellular Matrix Turnover and Fibrosis, Neurohormonal Signaling, and Cardiovascular Clinical and Epidemiology Assessments. Several articles also focused on establishing rigor and reproducibility of key physiological measurements involved in cardiovascular health and disease, as well as recommendations and considerations for study design. Combined, these articles summarize our current understanding of sex and gender influences on cardiovascular physiology and pathophysiology and provide insight into future directions needed to further expand our knowledge.

A review of the historical use of sex as a biological variable in the American Journal of Physiology-Heart and Circulatory Physiology

Despite National Institute of Health (NIH) mandates requiring sex as a biological variable (SABV), female underrepresentation persists in research, driving the American Journal of Physiology-Heart and Circulatory Physiology (Am J Physiol-Heart Circ) to publish SABV expectations in 2021. To determine progress within the Am J Physiol-Heart Circ, this mini-review evaluated SABV during the first 6 mo of each decade from 1980 to 2020, and 2019, to mitigate pandemic influence. Of the 1,205 articles published, 1,087 articles were included in this review (articles without original research subjects were excluded), of which 72.9% identified subjects. There were consistently fewer female human participants than males, except within 2019 (1980: females n = 3, males n = 5; 1990: females n = 70, males n = 199; 2000: females n = 305, males n = 355; 2010: females n = 186, males n = 472; 2019: females n = 1,695, males n = 1,550; 2020: females n = 1,157, males n = 1,222) and fewer female animals than males (1980: females n = 58, males n = 1,291; 1990: females n = 447, males n = 2,628; 2000: females n = 590, males n = 3,083; 2010: females n = 663, males n = 4,517; 2019: females n = 338, males n = 1,340; 2020: females n = 1,372, males n = 1,973). Only 16 (12.3%) articles including humans discussed SABV from 1980 to 2020. There are persistent SABV disparities within Am J Physiol-Heart Circ with some improvements in recent years. It is imperative that organizations such as the American Physiological Society and NIH foster an expectation of SABV as the norm, not the exception.