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 betwe en sodium-sensitive hypertension and microvessel density. Design: Seve nteen sodium-sensitive and 28 sodium-resistant young borderline hypert ensive males and 10 normotensive controls were studied. All of the sub jects ate a diet containing 120 mmol/day sodium during the week preced ing the investigation. Methods: Capillary density was investigated by means of intravital video-microscopy. Blood pressure, cardiac index, p lasma volume and humoral factors, such as plasma renin activity, plasm a aldosterone and atrial natriuretic peptide, were also determined. Re sults: No differences in capillary density were found under basal cond itions. However, during hyperaemia the sodium-resistant subjects had s ignificantly fewer perfused capillaries than both the sodium-sensitive and control subjects, whereas (apart from blood pressure) macrocircul atory parameters and humoral factors did not differ among the three gr oups. Conclusion: Sodium-resistant borderline hypertensives seem to be characterized by a (possibly structural) reduction in nailfold capill arity, a phenomenon that is, as yet, unexplained.