ニコチンがラット棘上筋腱の物質特性に及ぼす影響

概要

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Several studies have shown that nicotine has a detrimental effect on the development of rotator cuff tears. However, little has been known about its mechanism. The purpose of this study was to evaluate the effect of nicotine on the material properties of the supraspinatus tendon in a rat model. Twenty-seven rats were randomly assigned to three groups. Subcutaneously implanted osmotic pumps delivered two different concentrations of nicotine solution (high dose, 45 ng/ml: low dose, 22.5 ng/ml) or saline solution (controls) over a twelve-week period. The level of serum cotinine, a breakdown product of nicotine, was evaluated. Tensile testing was performed using the left supraspinatus tendon in each rat. The maximum load of the supraspinatus tendon was measured, and the maximum tensile stress and elastic modulus were calculated.Serum cotinine levels demonstrated controlled systemic release of nicotine. The maximum tensile load and stress did not show any significant differences among the three groups. However, the elastic modulus was higher in the nicotine groups than in the control group. A significant difference existed between the low-dose nicotine and control groups (P = 0.042). Nicotine caused a change in the material properties of the supraspinatus tendon in a rat model. This change, caused by nicotine administration, may be related to an occurrence of a tear in the supraspinatus tendon.