Hemodynamics of hypertensive animals.

With a model in which arterial pressure is a function of cardiac output and total peripheral resistance as the composite resistance of parallel regional peripheral resistances in mind, the measured values of these and other cardiovascular parameters in the SHR and other hypertensive animals are reviewed. In most studies, the hypertensive state is ascribable to an increased total peripheral resistance with almost normal cardiac output. Regional peripheral resistances are elevated diffusely in most hypertensive animals, but the extent is topographically different, as numerically demonstrated by the help of the indices proposed by the reviewer. Besides the elevation of flow resistance, decreases in compliance and volume in different parts of the cardiovascular system seem to be noteworthy hemodynamic findings. Several theories for development and maintenance of hypertension are also reviewed, and hypothetical modes of action of two representative antihypertensives, diuretics and beta-adrenoceptor blockers, are also briefly described.