The factors responsible for predisposition to progressive organ injury
and vascular complications in arterial hypertension are uncertain. Re
cent evidence shows that leukocytes participate in cardiovascular cond
itions for which hypertension is a risk factor. Therefore, there is a
need to define the properties of circulating leukocytes in hypertensiv
es. There are about twice as many circulating leukocytes in spontaneou
s hypertensive rats (SHRs) compared with their normotensive controls,
the Wistar-Kyoto rats (WKYs). The SHR neutrophils are viscoelastic and
similar to neutrophils in WKYs but exhibit lower deformability in sho
rt-term elastic deformation. Mature SHRs have elevated levels of spont
aneous pseudopod formation. Mild stimulation with N-formyl-Met-Leu-Phe
or platelet-activating factor (10(-8) M) results in a significantly e
nhanced level of neutrophil pseudopod formation in SHRs but not in WKY
s. SHRs exhibit higher levels of spontaneous superoxide formation. Alk
aline phosphatase content of individual circulating neutrophils in SHR
s is on average lower while plasma levels of alkaline phosphatase in t
he same samples are elevated in the SHRs. Spontaneous degranulation of
SHR neutrophils is also detectable with myeloperoxidase measurements.
Such activity of circulating leukocytes poses a significant risk for
vascular cytotoxicity in the hypertensive rats.