Nailfold capillary density in salt-sensitive and salt-resistant borderline hypertension.

OBJECTIVE

Nailfold capillary density was measured at rest and after 4 min circulatory arrest in order to investigate the relationship between sodium-sensitive hypertension and microvessel density.

DESIGN

Seventeen sodium-sensitive and 28 sodium-resistant young borderline hypertensive males and 10 normotensive controls were studied. All of the subjects ate a diet containing 120 mmol/day sodium during the week preceding the investigation.

METHODS

Capillary density was investigated by means of intravital video-microscopy. Blood pressure, cardiac index, plasma volume and humoral factors, such as plasma renin activity, plasma aldosterone and atrial natriuretic peptide, were also determined.

RESULTS

No differences in capillary density were found under basal conditions. However, during hyperaemia the sodium-resistant subjects had significantly fewer perfused capillaries than both the sodium-sensitive and control subjects, whereas (apart from blood pressure) macrocirculatory parameters and humoral factors did not differ among the three groups.

CONCLUSION

Sodium-resistant borderline hypertensives seem to be characterized by a (possibly structural) reduction in nailfold capillarity, a phenomenon that is, as yet, unexplained.