Sensitivity of pulmonary chemo reflexes and lung inflation reflexes to repetitive stimulation and to inhibition with lidocaine and morphine

Morphine compromises bronchial epithelial TLR2/IL17R signaling crosstalk, necessary for lung IL17 homeostasis

Opportunistic lung infection and inflammation is a hallmark of chronic recreational/clinical use of morphine. We show that early induction of IL17 from the bronchial epithelium, following pathogenic encounter is a protective response, which contributes to pathogenic clearance and currently attributed to TLR2 activation in immune cells. Concurrent activation of TLR2 and IL17R in bronchial epithelium results in the sequestration of MyD88 (TLR2 adapter) by Act1/CIKS (IL17R adapter), thereby turning off TLR2 signaling to restore homeostasis. Morphine inhibits the early IL17 release and interaction between Act1 and MyD88, leading to decreased pathogenic clearance and sustained inflammation. Hence, we propose that therapeutically targeting either TLR2 or IL17 in bronchial epithelia, in the context of morphine, can restore inflammatory homeostasis.

Reflex cardiovascular responses to lung inflation: a review

For almost one and a half centuries cardiovascular effects on lung inflation have been the subject of hot disputes. Despite numerous experimental and clinical investigations the problem has remained basically unsettled. The current review makes an attempt to bring out the main viewpoints concerning this subject and present some possible explanations for contradictions in the results of various studies.

Diaphragmatic vasodilation elicited by pulmonary C-fiber stimulation

This study was performed to assess the effect of pulmonary C-fiber stimulation with capsaicin on vascular resistance in the diaphragm. Nine dogs were anesthetized with pentobarbital sodium and were instrumented with right and left ventricular catheters. The left phrenic artery was isolated and perfused from an extracorporeal reservoir. Right ventricular capsaicin injections (5-20 micrograms/kg) caused significant decreases in phrenic perfusion pressure (-16%), systemic arterial pressure (-32%), and heart rate (-19%). Injection of identical doses of capsaicin into the left ventricle led to no significant changes in phrenic arterial perfusion pressure or systemic arterial pressure but a 10% decrease in heart rate. Bilateral cervical vagotomy eliminated the response to both right and left ventricular injection of capsaicin, as did administration of the autonomic ganglion blocker hexamethonium bromide. The results indicate that pulmonary C-fiber stimulation reflexly vasodilates vessels in the diaphragm.