PROPERTIES OF CIRCULATING LEUKOCYTES IN SPONTANEOUSLY HYPERTENSIVE RATS

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.