A.: Peripheral vascular hemodynamics in the bulbar conjunctiva of subjects with hypertensive vascular disease

Within recent years, methods have been devel-oped for direct observational studies concerned with functional aspects of the muscular vessels in the capillary bed of living small mammals of sev-eral species (1-3). With these technics, it has been found that certain objective criteria of periph-eiral vascular reactivity can be selected and fol-lowed during repeated examinations of the termi-nal vessels with the microscope.- Comparisons of the several different overall hemodynamic disturb-ances in the experimental animal (i.e., hyperten-sion, acute hemorrhage, prolonged hypotension) with their co-existent phenomena in the peripheral vascular system have shown that each separate condition thus far investigated has had a distinc-tive status reflected in the capillary bed of the mesentery. For example, acute hemorrhage was accompanied by widespread arteriolar and metar-teriolar constriction, capillary ischemia, and poor venular return. The reactivity of metarterioles and precapillary sphincters to topically applied epinephrine was augmented. Terminal prolonged hemorrhagic or traumatic hypotension, on the other hand, had a dilated capillary bed, with slug-gish arteriolar and venular blood flow, plethoric capillaries and diminished epinephrine responses (2, 4, 5). The mesenteric vascular bed in experi-mental renal hypertension was predominantly con-stricted, with ischemic arterioles and capillaries and a similar elevation of epinephrine response. In addition, it had a marked "hyperplasia " of vascu-lar elements (6). 1This work was supported in part by the Nutrition Foundation, New York, N. Y. 2Apparatus used for the study of the conjunctiva was obtained through a grant in aid from the American Philo