Data from: The role of gravity in the evolution of mammalian blood pressure

Understanding of the factors involved in determining the level of central arterial blood pressure in mammals has been clouded by inappropriate allometric analyses that fail to account for phylogenetic relationships among species, and require pressure to approach 0 as body size decreases. The present study analyses systolic, mean arterial, and diastolic blood pressure in 47 species of mammal with phylogenetically informed techniques applied to two-parameter equations. It also sets nonlinear, three-parameter equations to the data to remove the assumption of the two-parameter power equation that the smallest animals must have negligible blood pressure. These analyses show that blood pressure increases with body size. Nonlinear analyses show that mean blood pressure increases from 93 mmHg in a 10 g mouse to 156 mmHg in a 4 tonne elephant. The scaling exponent of blood pressure is generally lower than, though not significantly different from, the exponent predicted on the basis of the expected scaling of the vertical distance between the head and the heart. This indicates that compensation for the vertical distance above the heart is not perfect and suggests that the pressure required to perfuse the capillaries at the top of the body may decrease in larger species.学界对哺乳动物中枢动脉血压水平的决定因素的认知曾因不当的异速生长分析而受阻：这类分析未纳入物种间的系统发育关系，且默认当生物体体型减小时血压需趋近于0。本研究采用基于系统发育信息的分析方法，并结合双参数方程，对47种哺乳动物的收缩压、平均动脉压及舒张压展开分析。本研究同时为该数据集拟合非线性三参数方程，以摒弃双参数幂方程中“体型最小的动物血压可忽略不计”的不合理假设。上述分析结果表明，血压随体型增大而升高。非线性分析结果显示，平均动脉压从10克小鼠的93毫米汞柱，升高至4吨大象的156毫米汞柱。血压的异速生长指数普遍低于基于头心垂直距离预期异速关系所预测的指数，但二者并无显著差异。这表明机体对心脏上方垂直距离的血压补偿并不完善，同时提示，体型更大的物种其身体顶部毛细血管灌注所需的血压可能有所降低。