Anisodamine Hydrobromide Ameliorates Pulmonary Microcirculatory Dysfunction in Septic Rats

Pulmonary microcirculatory dysfunction is a hallmark of sepsis, contributing to hypoxemia, pulmonary edema, and multiple organ failure. Anisodamine hydrobromide (ADM), a natural alkaloid with anti-inflammatory and endothelial-protective properties, has been used clinically in China for septic shock. However, its effects on pulmonary microcirculatory dysfunction in septic shock remain unclear.

A rat model of sepsis was established via cecal ligation and puncture (CLP). Rats were treated with low, medium, or high doses of ADM. Seven-day survival rates and arterial blood gas parameters were monitored. Pulmonary microvascular leakage was evaluated using Evans blue extravasation and FITC-dextran imaging. Histological analysis, immunofluorescence, and Western blotting were performed to assess leukocyte adhesion, inflammatory cell infiltration, endothelial junction proteins, basement membrane proteins, and matrix metalloproteinases.

ADM treatment significantly improved 7-day survival and restored arterial partial pressure of oxygen (PaO₂), oxygen saturation (SaO₂), and pH in CLP rats. High-dose ADM markedly reduced Evans blue and FITC-dextran leakage, attenuated pulmonary edema, and preserved alveolar architecture. ADM inhibited leukocyte adhesion in pulmonary microvessels and decreased infiltration of MPO- and CD68-positive inflammatory cells. Mechanistically, ADM suppressed CLP-induced Caveolin-1 upregulation, restored the expression of VE-Cadherin, Occludin, and Claudin-5, and prevented degradation of Collagen IV and Laminin. Additionally, ADM significantly downregulated MMP-9 expression, while MMP-2 levels remained unchanged, suggesting a role in limiting junctional and basement membrane degradation.

ADM protects against CLP-induced pulmonary microcirculation dysfunction in rats by attenuating inflammatory cell infiltration, preserving pulmonary endothelial junctions, and maintaining basement membrane integrity. These results provide mechanistic insight into ADM's therapeutic potential in sepsis-induced pulmonary microcirculation dysfunction and support its use for sepsis in clinic.