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

Abstract

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.

Effects of Antihypertensive Drug Therapy on the Morphology and Mechanics of Resistance Arteries from Spontaneously Hypertensive Rats

“…The effects of these smaller vessels would be included in perfusion tests along with the larger arteries. The reasons for possibly excluding the arterioles arises partly from the recent work of Hertel et al (13). Their data actually pointed to a 41% decreased wall-to-lumen ration in 25-to 30-/rm arterioles of the SHR, and it would seem to us unlikely that relief of the pressure overload by treat ment would have worked in such a direction as to turn this decreased wall-to-lumen ratio in tire other direction.…”

Effects of chronic hypertension and sympathetic nerves on the cerebral microvasculature of stroke-prone spontaneously hypertensive rats.

“…Although elevated arterial pressure results in damage to tissues (Byrom, 1969;Limas et al, 1983), elevated resistance of large arteries could diminish the deleterious effects of hypertension by attenuation of elevated pressure in the microvasculature. It is known that pressure in precapillary arterioles of SHR is close to normal in most vascular beds (Hertel et al, 1978;Zweifach et al, 1981;Harper and Bohlen, 1984). It has been demonstrated previously that cerebral precapillary arteriolar pressure (Harper and Bohlen, 1984) and cerebral blood flow (Hoffman et al, 1982;Sadoshima et al, 1983) are near normal in SHR, which implies that resistance of large cerebral arteries is increased in SHR.…”

Relationships between Vessel Design and Hemodynamics along the Precapillary Resistance Compartment in Normo -and Hypertension

“…The first morpho logic data were, in fact, available even before blood pressure could be adequately measured in man (9). Because of some recent, apparently con flicting results (1,2,8) it seems desirable to integrate present hemodynamic and morpho metric data concerning the precapillary resis tance compartment in normo-and hypertensive conditions.…”

“…In the 'ex change section', mean capillary pressure (Pc), i.e. at the balance point between filtration and absorption during isogravimetry, is around 13 mm Hg in NCR skeletal muscle in vivo (10), but perhaps 2-3 mm Hg higher in SHR, judging from the 15-20% elevated filtration transfer of plasma protein in SHR (13) and from lymph flow studies (8). Therefore, at the point where the precapillary resistance and sphincter sec tions end and the capillary exchange section starts, pressure would be approximately 20 mm Hg in NCR and 25 mm Hg in SHR.…”

“…I). These latter data are based on morphometric estimations in man (7,14,16) and rats (1,2,8,11,12). Thus, precise compar isons of normo-and hypertensive resistance vessels in man during largely equal transmural pressures show a 70-80% w/T; elevation in proximal precapillary vessels of hypertensive subjects with a MAP increase of about 50% (7,16).…”