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The American Journal of Physiology: Regulatory, Integrative & Comparative Physiology has issued a call for papers on the topic of cardiovascular regulation during exercise, specifically focusing on the role of biological sex and the consequences of aging. The editors are seeking original research, short reports, and reviews that explore areas such as autonomic control of circulation, skeletal muscle, cerebral and cardiac blood flow, cardiac regulation, hemodynamic regulation, and thermal challenges. The aim is to better understand the sex-specific differences in cardiovascular responses to exercise and how they change throughout the lifespan. The call also emphasizes the need to consider the effects of aging, age-related diseases, and medications commonly prescribed to older adults on cardiovascular regulation during exercise. The editors encourage researchers to refer to recently published guidelines on the use of sex and gender in cardiovascular research. [Extracted from the article]

As we approach the centenary of the term "comparative physiology," we reexamine its role in modern biology. Finding inspiration in Krogh's classic 1929 paper, we first look back to some timeless contributions to the field. The obvious and fascinating variation among animals is much more evident than is their shared physiological unity, which transcends both body size and specific adaptations. The "unity in diversity" reveals general patterns and principles of physiology that are invisible when examining only one species. Next, we examine selected contemporary contributions to comparative physiology, which provides the context in which reductionist experiments are best interpreted. We discuss the sometimes surprising insights provided by two comparative "athletes" (pronghorn and rattlesnakes), which demonstrate 1) animals are not isolated molecular mechanisms but highly integrated physiological machines, a single "rate-limiting" step may be exceptional; and 2) extremes in nature are rarely the result of novel mechanisms, but rather employ existing solutions in novel ways. Furthermore, rattlesnake tailshaker muscle effectively abolished the conventional view of incompatibility of simultaneous sustained anaerobic glycolysis and oxidative ATP production. We end this review by looking forward, much as Krogh did, to suggest that a comparative approach may best lend insights in unraveling how skeletal muscle stores and recovers mechanical energy when operating cyclically. We discuss and speculate on the role of the largest known protein, titin (the third muscle filament), as a dynamic spring capable of storing and recovering elastic recoil potential energy in skeletal muscle. [ABSTRACT FROM AUTHOR]

The article discusses some of the recent advances in oxygen as a regulator of biological systems identified in the "American Journal of Physiology-Regulatory, Comparative and Integrative Physiology." It highlights the critical new concepts that have arisen in the hope that the interested reader will go to the original sources.