Telocytes (TC), a cell population located in the connective tissue of many organs of humans and laboratory mammals, are characterized by a small cell body and extremely long and thin processes. Different TC subpopulations share unique ultrastructural features, but express different markers. In the gastrointestinal (GI) tract, cells with features of TC were seen to be CD34‐positive/c‐kit‐negative and several roles have been proposed for them. Other interstitial cell types with regulatory roles described in the gut are the c‐kit‐positive/CD34‐negative/platelet‐derived growth factor receptor α (PDGFRα)‐negative interstitial cells of Cajal (ICC) and the PDGFRα‐positive/c‐kit‐negative fibroblast‐like cells (FLC). As TC display the same features and locations of the PDGFRα‐positive cells, we investigated whether TC and PDGFRα‐positive cells could be the same cell type. PDGFRα/CD34, PDGFRα/c‐kit and CD34/c‐kit double immunolabelling was performed in full‐thickness specimens from human oesophagus, stomach and small and large intestines. All TC in the mucosa, submucosa and muscle coat were PDGFRα/CD34‐positive. TC formed a three‐dimensional network in the submucosa and in the interstitium between muscle layers, and an almost continuous layer at the submucosal borders of muscularis mucosae and circular muscle layer. Moreover, TC encircled muscle bundles, nerve structures, blood vessels, funds of gastric glands and intestinal crypts. Some TC were located within the muscle bundles, displaying the same location of ICC and running intermingled with them. ICC were c‐kit‐positive and CD34/PDGFRα‐negative. In conclusion, in the human GI tract the TC are PDGFRα‐positive and, therefore, might correspond to the FLC. We also hypothesize that in human gut, there are different TC subpopulations probably playing region‐specific roles.

Urinary bladder voiding is a complex mechanism depending upon interplay among detrusor, urothelium, sensory and motor neurons and connective tissue cells. The identity of some of the latter cells is still controversial. We presently attempted to clarify their phenotype(s) in the human urinary bladder by transmission electron microscopy (TEM) and immunohistochemistry. At this latter aim, we used CD34, PDGFRα, αSMA, c‐Kit and calreticulin antibodies. Both, TEM and immunohistochemistry, showed cells that, sharing several telocyte (TC) characteristics, we identified as TC; these cells, however, differed from each other in some ultrastructural features and immunolabelling according to their location. PDGFRα/calret‐positive, CD34/c‐Kit‐negative TC were located in the sub‐urothelium and distinct in two subtypes whether, similarly to myofibroblasts, they were αSMA‐positive and had attachment plaques. The sub‐urothelial TC formed a mixed network with myofibroblasts and were close to numerous nerve endings, many of which nNOS‐positive. A third TC subtype, PDGFRα/αSMA/c‐Kit‐negative, CD34/calret‐positive, ultrastructurally typical, was located in the submucosa and detrusor. Briefly, in the human bladder, we found three TC subtypes. Each subtype likely forms a network building a 3‐D scaffold able to follow the bladder wall distension and relaxation and avoiding anomalous wall deformation. The TC located in the sub‐urothelium, a region considered a sort of sensory system for the micturition reflex, as forming a network with myofibroblasts, possessing specialized junctions with extracellular matrix and being close to nerve endings, might have a role in bladder reflexes. In conclusions, the urinary bladder contains peculiar TC able to adapt their morphology to the organ activity.

Therapeutic use of sulfhydrylated inhibitor S-zofenopril has raised different hypotheses regarding the role played by its thiol group in the beneficial clinical effects exerted compared with other angiotensin-converting enzyme (ACE) inhibitors. Here, we investigated hydrogen sulfide (H₂S) pathway as accountable for extra-beneficial effects in vascular function. Spontaneously hypertensive rat (SHRs) and control Wistar Kyoto (WKY) rats were treated with either S-zofenopril or enalapril in vivo. Aorta and carotid were harvested and ex vivo vascular reactivity to acetylcholine (Ach) and l-cysteine (l-cys) assessed. Cystathionine-β-synthase (CBS), cystathionine-γ-lyase (CSE), and 3-mercaptosulfur-transferase (3MST) expression, as well as H₂S levels, were evaluated in both vascular tissues. The vascular response to Ach in both carotid and aorta was impaired in SHR (∼30%, P < 0.001). S-zofenopril, but not enalapril, restored this response, while l-cys-induced relaxation was enhanced. CSE expression in vessels and tissue/plasma H₂S levels were restored to WKY values in SHRs receiving S-zofenopril. In contrast, CBS and 3MST expression were not modified by treatments. S-zofenoprilat, an active metabolite of S-zofenopril, releases H₂S in a ‘cell-free’ assay and it directly relaxed vessels in vitro in a concentration-dependent manner (P < 0.001). In vivo administration of R-zofenoprilat diasteroisomer, which does not inhibit ACE, did not modify blood pressure; nonetheless, it retained the beneficial effect on SHR vascular function as well as restored plasma/tissue H₂S levels. Our findings establish that S-zofenopril improves vascular function by potentiating the H₂S pathway in a model of spontaneous hypertension. This novel mechanism, unrelated to ACE inhibition and based on H₂S release, could explain the beneficial effects of sulfhydrylated ACE inhibitors reported in the clinical literature.

Observational studies indicate that topical application of ricinoleic acid (RA), the main component of castor oil, exerts remarkable analgesic and anti‐inflammatory effects. Pharmacological characterization has shown similarities between the effects of RA and those of capsaicin, suggesting a potential interaction of this drug on sensory neuropeptide‐mediated neurogenic inflammation. The aim of this study was to assess RA anti‐inflammatory activities in comparison with capsaicin in several models of acute and subchronic inflammation. The acute inflammation was induced by intradermal injection of carrageenan in the mouse or by histamine in the guinea‐pig eyelid. In either experiment, the extent of the oedema thickness was measured. Subchronic oedema was induced by complete Freund′s adjuvant injection in the ventral right paw of mice. Tissue substance P (SP) was measured in the carrageenan experiments by radioimmunoassay (RIA). It was found that the acute topical application of RA (0.9 mg/mouse) or capsaicin (0.09 mg/mouse) significantly increased the mouse paw oedema induced by carrageenan, while an 8‐day repeated topical treatment with the same doses of both compounds resulted in a marked inhibition of carrageenaninduced paw oedema matched by a reduction in SP tissue levels. Similar effects were found against histamine‐induced eyelid oedema in guinea‐pigs after acute or repeated application of RA or capsaicin. RA and capsaicin given for 1–3 weeks reduced the established oedema induced by Freund′s adjuvant, a subchronic model of inflammation, particularly if given by the intradermal route. Either in mouse paw or in guineapig eyelid, capsaicin but not RA by itself produced a slight hyperemia and activation of a behavioural response (e.g. scratching of the eyelids). On the basis of the present results, RA may be seen as a new capsaicin‐like, non‐pungent anti‐inflammatory agent suitable for peripheral application.

Background: Zofenopril, a sulfhydrylated angiotensin‐converting enzyme inhibitor (ACEI), reduces mortality and morbidity in infarcted patients to a greater extent than do other ACEIs. Zofenopril is a uniqueACEI that has been shown to increase hydrogen sulfide (H₂S) bioavailability and nitric oxide (NO) levels via bradykinin‐dependent signaling. Both H₂S andNOexert cytoprotective and antioxidant effects. We examined zofenopril effects on H₂S andNObioavailability and cardiac damage in murine and swine models of myocardial ischemia/reperfusion (I/R) injury.Methods and Results: Zofenopril (10 mg/kgPO) was administered for 1, 8, and 24 hours to establish optimal dosing in mice. Myocardial and plasma H₂S andNOlevels were measured along with the levels of H₂S andNOenzymes (cystathionine β‐synthase, cystathionine γ‐lyase, 3‐mercaptopyruvate sulfur transferase, and endothelial nitric oxide synthase). Mice received 8 hours of zofenopril or vehicle pretreatment followed by 45 minutes of ischemia and 24 hours of reperfusion. Pigs received placebo or zofenopril (30 mg/daily orally) 7 days before 75 minutes of ischemia and 48 hours of reperfusion. Zofenopril significantly augmented both plasma and myocardial H₂S andNOlevels in mice and plasma H₂S (sulfane sulfur) in pigs. Cystathionine β‐synthase, cystathionine γ‐lyase, 3‐mercaptopyruvate sulfur transferase, and total endothelial nitric oxide synthase levels were unaltered, while phospho‐endothelial nitric oxide synthase¹¹⁷⁷was significantly increased in mice. Pretreatment with zofenopril significantly reduced myocardial infarct size and cardiac troponin I levels afterI/R injury in both mice and swine. Zofenopril also significantly preserved ischemic zone endocardial blood flow at reperfusion in pigs after I/R.Conclusions: Zofenopril‐mediated cardioprotection duringI/R is associated with an increase in H₂S andNOsignaling.