Arteriolar hyalinosis does not interfere with the local veno-arteriolar reflex regulation of subcutaneous blood flow in insulin-dependent diabetic patients

Abstract

The function of the local nervous veno-arteriolar reflex regulation of blood flow in subcutaneous tissue of the lower leg was studied in diabetic patients. The material comprised 11 long-term insulin-dependent diabetic (IDDM) patients with retinopathy and nephropathy and eight short-term IDDM patients without retinopathy or nephropathy and 11 non-diabetic subjects. The diabetic patients had no or a slight to moderate degree of peripheral autonomic and sensoric neuropathy. Blood flow was measured by the local ¹³³Xe wash-out technique. Blood flow was determined before, during and after an approximately 40 mmHg increase in venous transmural pressure, induced by lowering the lower leg 50 cm below heart level. During lowering of the leg, the subcutaneous blood flow decreased to the same level in long-term IDDM patients (mean: 46%), short-term IDDM patients (53%) and control subjects (53%). There was no association between the relative local blood flow during lowering and the degree of terminal arteriolar hyalinosis studied in skin biopsies from the same tissue area. Our results suggest that terminal arteriolar hyalinosis does not interfere with the local sympathetic-mediated veno-arteriolar reflex regulation of blood flow. Moreover, the vasoconstriction mediated by the veno-arteriolar reflex probably occurs in the larger arterioles (>50–100 μm) or small arteries.

Key words:

• diabetic microangiopathy
• microcirculation
• nervous regulation
• orthostatic pressure changes
• subcutaneous blood flow
• sympathetic axon reflex
• type 1 diabetes