This study examined the autophagy and apoptosis of vascular endothelial cells in spontaneously hypertensive rats (SHRs) under intermittent heat stress and determined whether the AMP-activated protein kinase (AMPK)/mammalian target of rapamycin (mTOR)/Unc-51 like autophagy activating kinase (ULK1) pathway is involved in autophagy regulation. Wistar-Kyoto (WKY) rats were assigned to control (WKY-CN), intermittent heat stress (WKY-8), and continuous heat stress (WKY-24) groups. SHRs were also assigned to three groups: SHR-CN, SHR-8, and SHR-24. Western blotting assay, immunohistochemical assay, and immunofluorescence assay were performed for observing expression of proteins related to autophagy and apoptosis and the AMPK/mTOR/ULK1 pathway. Vascular endothelial cells underwent autophagy and apoptosis following heat stress, as revealed by high expression of autophagy- and apoptosis-related proteins. Heat stress elevated AMPK and ULK1 expression levels, whereas it decreased mTOR phosphorylation in SHR-8 and SHR-24 groups. Finally, the rats in SHR-8 group were administered an autophagy inducer (rapamycin, Rapa) and inhibitor (3-Methyladenine, 3-MA), respectively, for evaluating autophagy induction and inhibition. Following Rapa administration, LC3-II/LC3-I and Caspase-3 expression levels were elevated in the intermittent heat stress groups as compared to those in the control groups; in contrast, 3-MA attenuated cell death in the intermittent heat stress groups. Overall, this study demonstrated that intermittent heat stress elicits autophagy and apoptosis processes in vascular endothelial cells and that the AMPK/mTOR/ULK1 pathway participates in regulating autophagy and apoptosis.

Peripheral artery disease (PAD) is a global health challenge, with current diagnostic methods, including the ankle-brachial index (ABI), having limitations, particularly in patients with arterial calcification. Near-infrared spectroscopy (NIRS) offers potential advantages as a non-invasive assessment tool, yet its clinical utility in PAD remains underexplored. This pilot study evaluated NIRS for differentiating between non-ischemic upper limbs and ischemic lower limbs, and assessed NIRS correlation with ABI. To do that, we performed an observational, cross-sectional study employing a convenience sample of 51 patients with PAD attending the vascular surgery outpatient clinic. A portable spectrometer recorded NIRS measurements from the right thumb and both halluces at rest. Random Forest classification was implemented to differentiate upper and lower limbs, revealing distinct NIRS patterns between upper and lower limbs, with an area under the ROC curve of 0.91 (95% CI 0.88-0.94). Interval Partial Least Squares regression (iPLS) identified wavelength regions correlating with ABI, with the 1429-1463nm interval being the most informative for ABI prediction, with a modest correlation (R2=0.167, RMSECV=0.186). NIRS demonstrated strong discriminative capability between non-ischemic upper and ischemic lower limbs in PAD. While the correlation between NIRS and ABI was modest, it suggests potential clinical relevance. These findings indicate that NIRS could be a rapid, portable, non-invasive complementary tool for PAD assessment.