Dept. of Anatomy and Physiology, Kansas State Univ., Manhattan, KS 66506, USA.
Am J Physiol Regul Integr Comp Physiol. 2010 Dec;299(6):R1555-63. doi: 10.1152/ajpregu.00434.2010. Epub 2010 Sep 15.
Sympathetic nerve discharge (SND) responses to hyperthermia are attenuated in aged rats without heart failure (HF) and in young HF (Y(HF)) rats, demonstrating that individually aging and HF alter SND regulation. However, the combined effects of aging and HF on SND regulation to heat stress are unknown, despite the high prevalence of HF in aged individuals. We hypothesized that SND responses to heating would be additive when aging and HF are combined, demonstrated by marked reductions in SND and mean arterial pressure (MAP) responses to heating in aged HF (A(HF)) compared with aged sham HF (A(SHAM)) rats, and in A(HF) compared with Y(HF) rats. Renal and splenic SND responses to hyperthermia (colonic temperature increased to 41.5°C) were determined in anesthetized Y(HF), young sham (Y(SHAM)), A(HF), and A(SHAM) Fischer rats. HF was induced by myocardial infarction and documented using echocardiographic, invasive, and postmortem measures. The severity of HF was similar in Y(HF) and A(HF) rats. SND responses to heating were attenuated in Y(HF) compared with Y(SHAM) rats, demonstrating an effect of HF on SND regulation in young rats. In contrast, A(HF) and A(SHAM) rats demonstrated similar SND responses to heating, suggesting a prominent influence of age on SND regulation in A(HF) rats. Splenic SND and MAP responses to heating were similar in Y(HF), A(HF), and A(SHAM) rats, indicating that the imposition of HF in young rats changes the regulatory status of these variables to one consistent with aged rats. These data suggest that the effect of HF on SND regulation to hyperthermia is age dependent.
交感神经放电（SND）对发热的反应在无心力衰竭（HF）的老年大鼠和年轻心力衰竭（Y（HF））大鼠中减弱，表明单独衰老和 HF 改变了 SND 调节。然而，尽管老年人 HF 的发病率很高，但衰老和 HF 对热应激 SND 调节的综合影响尚不清楚。我们假设，当衰老和 HF 结合时，SND 对加热的反应将是累加的，这表现为与年轻假手术 HF（Y（SHAM））大鼠相比，SND 和平均动脉压（MAP）对加热的反应明显降低，与 Y（HF）大鼠相比，A（HF）大鼠也明显降低。在麻醉的 Y（HF）、年轻假手术（Y（SHAM））、A（HF）和 A（SHAM）费舍尔大鼠中，确定了肾脏和脾脏 SND 对发热（直肠温度升高至 41.5°C）的反应。HF 通过心肌梗死诱导，并通过超声心动图、有创和死后测量来记录。Y（HF）和 A（HF）大鼠的 HF 严重程度相似。与 Y（SHAM）大鼠相比，Y（HF）大鼠的 SND 对加热的反应减弱，这表明 HF 对年轻大鼠 SND 调节有影响。相比之下，A（HF）和 A（SHAM）大鼠对加热的 SND 反应相似，这表明年龄对 A（HF）大鼠 SND 调节有显著影响。在 Y（HF）、A（HF）和 A（SHAM）大鼠中，脾脏 SND 和 MAP 对加热的反应相似，这表明在年轻大鼠中施加 HF 会改变这些变量的调节状态，使其与老年大鼠一致。这些数据表明，HF 对发热时 SND 调节的影响取决于年龄。
