Work

Hepatic and Pulmonary Vasoactive Response Triggered by Potentially Hazardous Chemicals After Passing Through the Gut Mucosa

Year: 2025

Type: article

Abstract: Background/Objectives: In a previous study, we observed significantly prolonged hepatic and pulmonary first-pass transit times (TTs) for 99mTc-pertechnetate absorbed through the colorectal mucosa during per-rectal portal scintigraphy (PRPS). These effects were not observed when 99mTc-pertechnetate was administered into the spleen during trans-splenic portal scintigraphy or injected intravenously in radionuclide angiocardiography. We hypothesized that 99mTc-pertechnetate is recognized in the colorectal mucosa as a potentially hazardous chemical (PHC), with its transhepatic and transpulmonary slowdown aiding in its removal. A similar reduction in portal flow, triggered by vasoactive circulating mediators, occurs during early metastasis of colorectal cancer (CRC), as indicated by a pathological increase in the hepatic perfusion index calculated using liver angioscintigraphy (LAS). We aimed to examine the hepatic and pulmonary vasoactive response triggered by PHCs after they pass through the gut mucosa and assess their pathological activation in early CRC metastasis. Methods: We measured TTs to determine whether hepatic and pulmonary vasoconstriction occurs in response to radiotracers administered at different sites. PRPS using 99mTc-pertechnetate evaluated the liver transit time (LTT) and right heart-to-liver circulation time (RHLT) of the colorectal-absorbed 99mTc-pertechnetate. LAS assessed RHLT and LTT following the intravenous injection of radiotracers based on 99mTc. Lower rectum transmucosal dynamic scintigraphy (LR-TMDS) measured RHLT of 99mTc-pertechnetate delivered into the lower rectum submucosa. LTT and RHLT were compared to similar TTs observed by other imaging methods. Results: In healthy volunteers, PRPS showed notably longer LTT (average: 24 s) and RHLT (average: 42 s) for colorectal-absorbed 99mTc-pertechnetate. Significantly lower RHLT values (9–13.5 s) were observed for 99mTc-pertechnetate and 99mTc-HDP (hydroxyethylene-diphosphate) administered intravenously during LAS, as well as for 99mTc-pertechnetate injected into the submucosa at LR–TMDS (12–15 s). The LTT assessed at LAS for 99mTc-HDP given intravenously ranged from 22 to 27 s, consistent with the range seen at PRPS for 99mTc-pertechnetate after colorectal absorption. Conclusions: An intense vasoconstriction happens in the liver and lungs when foreign substances, recognized by the body as PHCs, pass through the gut mucosa, helping their elimination.

Source: Diagnostics

DOI: 10.3390/diagnostics15192444

Authors: Mircea Dragoteanu, Ștefan Tolea, Ioana Duca, Raluca Mititelu, Kalevi Kairemo