Evidence for involvement of catecholamines in the effect of morphine on ventricular automaticity in the rat

Intracellular Salmonella Paratyphi A is motile and differs in the expression of flagella-chemotaxis, SPI-1 and carbon utilization pathways in comparison to intracellular S. Typhimurium

Although Salmonella Typhimurium (STM) and Salmonella Paratyphi A (SPA) belong to the same phylogenetic species, share large portions of their genome and express many common virulence factors, they differ vastly in their host specificity, the immune response they elicit, and the clinical manifestations they cause. In this work, we compared their intracellular transcriptomic architecture and cellular phenotypes during human epithelial cell infection. While transcription induction of many metal transport systems, purines, biotin, PhoPQ and SPI-2 regulons was similar in both intracellular SPA and STM, we identified 234 differentially expressed genes that showed distinct expression patterns in intracellular SPA vs. STM. Surprisingly, clear expression differences were found in SPI-1, motility and chemotaxis, and carbon (mainly citrate, galactonate and ethanolamine) utilization pathways, indicating that these pathways are regulated differently during their intracellular phase. Concurring, on the cellular level, we show that while the majority of STM are non-motile and reside within Salmonella-Containing Vacuoles (SCV), a significant proportion of intracellular SPA cells are motile and compartmentalized in the cytosol. Moreover, we found that the elevated expression of SPI-1 and motility genes by intracellular SPA results in increased invasiveness of SPA, following exit from host cells. These findings demonstrate unexpected flagellum-dependent intracellular motility of a typhoidal Salmonella serovar and intriguing differences in intracellular localization between typhoidal and non-typhoidal salmonellae. We propose that these differences facilitate new cycles of host cell infection by SPA and may contribute to the ability of SPA to disseminate beyond the intestinal lamina propria of the human host during enteric fever.

Salmonella enterica is a ubiquitous, facultative intracellular animal and human pathogen. Although non-typhoidal Salmonella (NTS) and typhoidal Salmonella serovars belong to the same phylogenetic species and share many virulence factors, the disease they cause in humans is very different. While the underlying mechanisms for these differences are not fully understood, one possible reason expected to contribute to their different pathogenicity is a distinct expression pattern of genes involved in host-pathogen interactions. Here, we compared the global gene expression and intracellular phenotypes, during human epithelial cell infection of S. Paratyphi A (SPA) and S. Typhimurium (STM), as prototypical serovars of typhoidal and NTS, respectively. Interestingly, we identified different expression patterns in key virulence and metabolic pathways, cytosolic motility and increased reinvasion of SPA, following exit from infected cells. We hypothesize that these differences contribute to the invasive and systemic disease developed following SPA infection in humans.

Interaction of U-50,488H and noradrenergic systems on isolated right atria

1. The present study examined the effect of U-50,488H on auricular rate on isolated right atria of the rat. 2. The negative chronotropic action induced by the kappa-agonist (U-50,488H) was potentiated by propranolol (10(-8) or 5 x 10(-8) M) or yohimbine (5 x 10(-7) or 10(-6) M) and in reserpinized rats (5 mg/kg i.p. 24 h before the experiments). 3. These results suggest that catecholaminergic mechanisms are involved in the cardiac depressant effect induced by U-50,488H.

Effects of morphine on isolated right atria of the rat

1. The present study describes the effects of morphine in the absence or presence of naloxone or atropine in the isolated right atria of the rat. 2. Morphine significantly decreased the auricular chronotropism. 3. The maximal effect was 10 +/- 1.0%. 4. Similar results were obtained in reserpinized animals (13 +/- 0.2% maximum). 5. Naloxone (5 x 10(-7) or 5 x 10(-6) M) did not change the inhibitory effects induced by morphine. 6. The maximal effect obtained with morphine in the presence of atropine (5 x 10(-7) M) was 9 +/- 0.1% similar to that obtained with morphine alone. 7. These results suggest that opioid or vagal mechanisms may not be involved in the cardiac inhibitory effects induced by morphine.