Identifying and evaluating patterns in cardiorespiratory physiology

Abstract

A major theme of many papers in this symposium is the identification of broad physiological trends and patterns that extend beyond the boundaries of data from individual studies. Recognizing patterns in everything from hypoxic ventilatory patterns to regulation of blood gases not only helps the investigator understand specific data sets, but also helps place those data in a broad context. Yet, recognizing physiological patterns is confounded by two factors: phylogenetic relationships and physiological state. Fortunately, the last decade has seen infiltration of sound evolutionary theory, including tools of cladisitic analysis and population genetics, into more and more studies of comparative physiology. However, even when an experimenter carefully accounts for phylogeny, differences in physiological state in the experimental animals can still obscure physiological patterns. Two informal categories of physiological state are described, the first obvious and frequently controlled for, and the second less obvious and typically not controlled for. Examples of the latter, including seasons, rhythms, prandial effects and sex of the animal, are developed to show how ignoring these can lead to considerable misleading variation in cardiorespiratory data sets. Considering physiological state is vital in producing reliable data that can be used meaningfully for delineating broad physiological patterns.