Impaired Microvascular Response to Muscle Stretching in Chronic Smokers With Type 2 Diabetes

Abstract

Objective: Cigarette smoking promotes endothelial dysfunction and is a prominent catalyst for vascular disease. This study employed laser doppler flowmetry (LDF) and spectral analysis to investigate the skin microvascular response to relatively mild stimulus of stretching in diabetic smokers. Methods: The study population consisted of thirty type 2 diabetic male patients (15 smokers vs. 15 non-smokers) and 15 normal non-smoking subjects. The cutaneous blood flow of the calf at both lower limbs was measured by LDF at a supine position throughout and after muscle stretching by passive dorsiflexion of the ankle. Results: Following the stretch, post-stretch reactive hyperemia (PSRH) responses were found in all subjects. However, the diabetic non-smokers had relatively higher reactive blood flow than that of the diabetic smokers. The PSRH sustained for a longer time in both diabetic non-smokers and non-diabetic non-smokers in the time domain analysis. By spectral analysis, an observed discrepancy between that of diabetic smokers and diabetic non-smokers was statistically significant. Specifically, the frequency intervals corresponded to a nitric oxide dependent endothelial activity. In addition, an excessive response induced by stretching in frequency intervals of neurogenic activity, when compared with the non-smoking control, was found on diabetic non-smokers. Conclusion: All subjects expressed the PSRH effect in cutaneous microcirculation after a 10-s stretch stimulus; however, this effect was observed at a significantly lower intensity in chronic smokers with diabetes. The spectral analysis of the skin blood flow signals provides a pathological index for the assessment of the endothelial dysfunction induced by cigarette smoking. Furthermore, the discrepancy of neurovascular function between that of diabetic non-smokers and normal subjects could also be distinguished via the variations of the spectrum related to neurogenic activity.

Reactive Hyperemia and Cardiovascular Autonomic Neuropathy in Type 2 Diabetic Patients: A Systematic Review of Randomized and Nonrandomized Clinical Trials

“…Of the articles reviewed herein, five showed differences in RH between healthy subjects and diabetic patients with and/or without neuropathy [15,30,33,57,58], while one study did not show such differences between healthy subjects and diabetic patients, but patients with diabetic ulcers had lower RH index values compared to healthy controls [59]. Another study found no significant difference in blood flow after a muscle strain that induced reactive hyperemia (PSRH) between normal subjects and diabetic non-smokers [43]. This different result (Table 2) may be due to the fact that a different methodology was used to induce and measure reactive hyperemia.…”

“…This different result (Table 2) may be due to the fact that a different methodology was used to induce and measure reactive hyperemia. However, there were significant differences between diabetic smokers and diabetic non-smokers and between diabetic smokers and normal subjects [43]. Therefore, there is a negative effect (independent) of tobacco on endothelial function.…”

“…Reactive hyperemia (RH) refers to the increase in blood flow in a given vascular territory that generally occurs in response to a period of arterial occlusion [20,[36][37][38][39][40][41][42] but can also occur after the passive distension of muscles (PSRH) [43]. The mechanisms underlying this response have not been fully elucidated, but prostaglandins and other metabolic and endothelial vasodilators, as well as sensory nerves, are thought to play a role.…”

“…Nine studies (Table 2) compared reactive hyperemia between diabetic patients with and without CAN [15,20,30,43,[58][59][60][61][62]. Four of them measured reactive hyperemia using PAT [15,59,61,62], and only two found a significantly lower endothelial-function-derived measure of PAT in diabetic patients with CAN than in those without CAN [15,59].…”

“…No significant differences in FMD% were reported between diabetic patients with and without CAN [30,58,60,62]. Two studies measured reactive hyperemia using laser Doppler techniques [20,43]. One of them found significant differences in the blood flow of the calf skin after a stretch between diabetic nonsmokers and smokers.…”