Is the extracellular matrix an integral and dynamic component of the sodium and water homeostatic system?

This hypothesis questions the validity of Starling's hypothesis regarding the distribution of water and electrolytes between the intravascular and interstitial compartments. It emphasises the potential importance of the gel state of the extracellular matrix in determining interstitial compliance and the distribution of water and electrolytes between the intravascular and interstitial compartments. Because the physicochemical properties of the extracellular matrix can change rapidly in response to numerous stimuli, it is suggested that the extracellular matrix is an integral and dynamic component of the sodium homeostatic system.

The extra-cellular-matrix in hypertension: the link between renal function, autoregulation and sodium metabolism, a review and hypothesis.

In this paper the nature of the extra-cellular-matrix (ECM) is outlined briefly. Changes in the ECM in hypertension have been reviewed as has their possible involvement in the pathophysiological process of hypertension. It appears that significant and widespread changes occur in the ECM in hypertensive states. Such changes may alter the characteristics of (1) the renal perfusion pressure/sodium excretion curve (2) autoregulation and (3) sodium metabolism, all of which have been implicated in the pathogenesis of hypertension. The ECM may well be the link between these three. The ECM changes will also contribute to many of the differences, e.g. altered fluid distribution, altered handling of a sodium load, altered electrolyte and water content of vascular tissue, and altered passive and active mechanical properties of vascular tissue seen in hypertensive states. The ECM changes are unlikely to be the root cause of hypertension but are a more fundamental difference than altered renal perfusion/excretion characteristics, altered fluid distribution etc. Indeed the perfusion/excretion characteristics, fluid distribution etc. appear to be dependent upon the properties of the ECM. What now requires to be done is to determine what controls the properties of the ECM and to determine what fault in the control may lead to the changes which could ultimately manifest themselves as hypertension.

Hormones, salt, hypertension and the interstitium. Is the interstitium the missing link?

The pathophysiology of most forms of hypertension is still poorly understood. A hypothesis is developed suggesting that the balance of hormones capable of influencing sodium metabolism play a significant role in the pathophysiology of hypertension, and that a significant component of the hormonal effect is mediated through changes in the interstitial matrix. It is suggested that the interstitial changes play a direct role in the increase in blood pressure and in bringing about many of the observed differences between hypertensive and normotensive states.