Altered lymphatic function and architecture in salt-induced hypertension assessed by near-infrared fluorescence imaging.

The lymphatic system plays an important role in maintaining the fluid homeostasis between the blood vascular and interstitial tissue compartment and there is recent evidence that its transport capabilities may regulate blood pressure in salt-induced hypertension. Yet, there is little known how the lymphatic contractile function and architecture responds to dietary salt-intake. Thus, we longitudinally characterized lymphatic contractile function and vessel remodeling noninvasively using dynamic near-infrared fluorescence imaging in animal models of salt-induced hypertension. The lymphatics of mice and rats were imaged following intradermal injection of indocyanine green to the ear tip or the base of the tail before and during two weeks of either a high salt diet (HSD) or normal chow. Our noninvasive imaging data demonstrated dilated lymphatic vessels in the skin of mice and rats on a HSD as compared to their baseline levels. In addition, our dynamic imaging results showed increased lymphatic contraction frequency in HSD-fed mice and rats. Lymphatic contractile function and vessel remodeling occurs in response to salt-induced hypertension suggesting a possible role for the lymphatics in the regulation of vascular blood pressure.