Peripheral artery disease (PAD) is primarily caused by occlusion of arteries that supply blood to the lower limbs and presents significantly pathological changes of calf muscles, include degenerating and regenerating fibers, reduction of the skeletal muscle area, connective tissue proliferation and fibrosis, fat accumulation, and abnormal mitochondria, all of which are predictors of muscle functional decline. Additionally, skeletal muscles also require the motor nerve innervation for the signal transmission through the neuromuscular junction (NMJ) to induce skeletal muscle contraction. To observe whether the NMJ is changed in the PAD patients, gastrocnemius muscles were collected from 5 health subjects, 39 patients with PAD stage I/II, and 17 patients with PAD stage III/IV. The motor nerve terminals were labeled with anti-neurofilament 200 and anti-synaptophysin antibodies, the nicotinic acetylcholine receptors (nAChRs) were labeled with α-Bungarotoxin. Labeled NMJs were imaged using a laser scanning confocal microscope with Z-stack. The image was captured in 597 NMJs from health subjects, 3115 NMJs from patients with PAD stage I/II, and 692 NMJs from patients with PAD stage III/IV, respectively. The total nAChR area and the number of discrete fragments of each nAChR cluster, the area per fragment, the percentage of fragmented nAChR clusters, the nerve innervation and the nerve terminal occupancy were calculated. The results were represented with mean ± standard error (SE); the total nAChR area per nAChR cluster was 365.6 ± 11.8 µm2, 416.6 ± 20.5 µm2, and 251.8 ± 19.1 µm2; the average number of fragment/ nAChR cluster was 2.6 ± 0.2, 4.5 ± 0.3, and 3.5 ± 0.3; the fragmented nAChR clusters were 9.4 ± 1.8%, 38.8 ± 3.4, and 28.1 ± 4.7; the area of each discrete fragment is 213.1 ± 17.6 µm2, 137.8 ± 6.4 µm2, and 100.4 ± 8.1 µm2; and the nerve terminal occupancy was 59.6 ± 1.9 %, 52.3 ± 1.1 %, and 50.7 ± 2.2 in the health subjects, PAD I/II, and PAD III/IV patients, respectively. All nAChR clusters were innervated by the motor nerve terminal in the health subjects, whereas 3.9 ± 2.6 % and 5.8 ± 1.9 % of nAChR clusters were denervated in PAD I/II and PAD III/IV patients, respectively. These data indicate that fragmented nAChR clusters are increased in PADI/II and PAD III/IV; the total nAChR area per nAChR cluster is increased in PAD I/II patients, however, the area of each discrete fragment is reduced because of fragmentation of NMJ; both the total nAChR area per nAChR cluster and the area of each discrete fragment are reduced in PAD III/IV patients. Additionally, the denervation of nAChR clusters is increased in PAD patients. These results suggest that the neuromuscular transmission is compromised in with PAD development, which limits PAD patients’ physical activities. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.
Tu et al. (Fri,) studied this question.