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Nailfold capillary density in salt-sensitive and salt-resistant borderline hypertension
P Draaijer1, P W de Leeuw, J P van Hooff
1Cardiovascular Research Institute, University of Limburg, Maastricht, The Netherlands.
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.