Intravital measurement of arteriolar pressure and tangential wall stress in normotensive and spontaneously hypertensive rats (established hypertension).

Under intravital conditions, intravascular pressures of mesenteric resistance vessels were measured in normotensive (NR, mean blood pressure 92 mm Hg) and spontaneously hypertensive rats (SHR, 161 mm Hg) being elevated over all by about 75%; the tangential wall stress (sigma = p.r/h; p represents the intravascular pressure and r/h the ratio of internal radius to wall thickness) was found to be increased by 120-140% in SHR.