The responsiveness of the microvasculature and arteries during cerebral cortical autoregulation in rats was determined from measurements of microvascular pressures and blood flow as the systemic arterial pressure was altered. At systemic arterial pressures from 65 to 155 mmHg, cortical blood flow was essentially constant. Arterioles with a resting internal diameter of 20-70 microns responded by nearly equal proportional changes in diameter over this pressure range, but microvascular pressures were a linear function of arterial pressure. The percent of control changes in arterial and microvascular resistances at systemic pressures from 80 to 180 mmHg were nearly identical. Therefore, the microvasculature and arterial vasculature were approximately equally responsive to changes in arterial pressure over most of the autoregulatory pressure range. In addition, the arterial vasculature controlled 45-50% of the total vascular resistance at systemic arterial pressures from 40 to 180 mmHg. These data indicate that the cerebral vascular autoregulation in the rat depended substantially on the approximately equal responsiveness of the arterial vasculature and microvasculature. Similar results have been reported in cats and may indicate a common form of cerebral vascular control, which involves both the microvasculature and brain arteries among different species.

The effect of chronic, severe diabetes mellitus on the morphology, blood flow regulation, and tissue PO2 of the cerebral cortex was evaluated in adult rats. The arterioles of the diabetic animals were enlarged in terms of both lumen diameter and vessel wall area. Although resting blood flow in the diabetic rats was greater than in the normal rats, the autoregulation of cerebral blood flow was very good within an arterial pressure range of 40-150 mmHg, just as in normal rats. The resting tissue PO2 in diabetic rats was 14.9 +/- 0.5 (SEM) compared with 12.7 +/- 0.6 mmHg in normal animals and in both groups remained at or near the resting PO2 at arterial pressures from 40 to 150 mmHg. There was no apparent loss of arterioles on the cortex surface or change in length of individual arterioles in diabetic animals but there was a 20-30% decrease in the number of venules and no change in the length of individual venules. These data indicate that although the arteriolar morphology and number of venules change in the brain during diabetes, physiological function in terms of tissue PO2 and blood flow regulation is maintained within normal limits.

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Thomas Aquinas consistently maintains that there are two kinds of beauty: bodily or sensible beauty and spiritual or intelligible beauty. Due to the lively debate over whether intelligible beauty is a transcendental for Thomas, discussions of his aesthetics have tended either to ignore his views on sensible beauty or to mention them only in passing. The present paper will therefore give a brief overview of Thomas’s thought on bodily beauty. The first section will discuss the objective aspects of sensible beauty for Thomas, i.e., its definition and three conditions, while the second will present his views on its subjective aspects, i.e., how we experience it, why it pleases us, and its importance for human flourishing. The third and final section will examine how Thomas’s account of sensible beauty affects his views on the beauty of the glorified human body and of the universe as a whole after the Last Judgment.

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