Resistance vessels in hypertension

Hypertension differentially affects the functional behavior of the mesenteric resistance arteries compared with similar sized arteries from the cerebral vascular autoregulatory bed. Antihypertensive drug treatment may, or may not, reverse the vascular wall structural composition and smooth muscle cell receptor sensitivity and contractile properties. These effects depend on the agent used, the length of treatment, and the vascular bed. Rat brain resistance arteries are myogenic at transmural pressures that are similar to those measured in autoregulatory, in vivo flow studies, as is the elevation of this range as a consequence of hypertension. The methods we have developed afford the investigator quantitative control over the variables that might affect the function of resistance vessels when tested in vitro. These techniques maintain the vessel close to physiological, in vivo conditions, and are useful tools for unraveling the complex mechanisms that define both, the normal vessel properties, and those of the vessel which has undergone modifications as a result of hypertension. Whether the vascular changes that we find in the SHR rat model parallel those which occur in human essential hypertension must yet be ascertained.