Christian Moro

Urothelial/lamina propria spontaneous activity and the role of M3 muscarinic receptors in mediating rate responses to stretch and carbachol

OBJECTIVE To investigate the effects of tissue stretch and muscarinic receptor stimulation on the spontaneous activity of the urothelium/lamina propria and identify the specific receptor subtype mediating these responses. METHODS Isolated strips of porcine urothelium with lamina propria were set up for in vitro recording of contractile activity. Muscarinic receptor subtype-selective antagonists were used to identify the receptors influencing the contractile rate responses to stretch and stimulation with carbachol. RESULTS Isolated strips of urothelium with lamina propria developed spontaneous contractions (3.7 cycles/min) that were unaffected by tetrodotoxin, Nω-nitro-L-arginine, or indomethacin. Carbachol (1 μM) increased the spontaneous contractile rate of these tissue strips by 122% ± 27% (P < .001). These responses were significantly depressed in the presence of the M3-selective muscarinic antagonist 4-diphenylacetoxy-N-methylpiperidine methiodide (10-30 nM) but were not affected by the M1-selective antagonist pirenzepine (30-100 nM) or the M2-selective antagonist methoctramine (0.1-1 μM). Stretching of the tissue also caused an increase in the spontaneous contractile rate, and these responses were abolished by atropine (1 μM) and low concentrations of 4-diphenylacetoxy-N-methylpiperidine methiodide (10 nM). Darifenacin, oxybutynin, tolterodine, and solifenacin (1 μM) all significantly depressed the frequency responses to carbachol (1 μM). CONCLUSION The urothelium with the lamina propria exhibits a spontaneous contractile activity that is increased during stretch. The mechanism appears to involve endogenous acetylcholine release acting on M3 muscarinic receptors. Anticholinergic drugs used clinically depress the responses of these tissues, and this mechanism might represent an additional site of action for these drugs in the treatment of bladder overactivity.

Contractile activity of the bladder urothelium/lamina propria and its regulation by nitric oxide

In the bladder, nitric oxide (NO) is released from neuronal and non-neuronal sources, but its actions are unclear. Strips of urothelium plus lamina propria contract in response to agonists and develop spontaneous phasic contractions, and the aim of this study was to investigate the influence of NO on this activity. Isolated strips of urothelium/lamina propria from porcine bladder developed spontaneous contractions (3.5 ± 0.3 cycles/min) and contracted in response to carbachol and electrical field stimulation (EFS). The NO synthase inhibitor N(ω)-nitro-l-arginine (L-NNA, 100 μM) had no effects on the tissues, but the NO donors diethylamine NONOate (DEANO, 100 μM) and nitroprusside (10 μM) caused relaxation, slowed the spontaneous rate of contractions and inhibited responses to carbachol. Maximum tonic contractions to carbachol were reduced by 17 ± 4% (P<0.001) and 35 ± 5% (P<0.001) by DEANO and nitroprusside respectively and the potency of carbachol was also reduced. Carbachol also increased the spontaneous frequency of contraction and these rate responses were again inhibited by DEANO and nitroprusside, but unaffected by L-NNA. Similarly, responses to EFS were significantly depressed (52-70%) by DEANO (P<0.05), but were unaffected by L-NNA. These data demonstrate spontaneous contractile activity and also nerve and agonist-induced tonic contractile activity within the urothelium and lamina propria. This activity is sensitive to depression by NO, but NO does not appear to be spontaneously released to influence this activity, nor does it appear to be released by muscarinic receptor stimulation. However the results suggest that in situations where NO production is increased, NO can influence the contractile activity of this tissue.

Adrenoceptor function and expression in bladder urothelium and lamina propria

OBJECTIVE To investigate the role of adrenoceptor subtypes in regulating the spontaneous contractile activity of the inner lining of the urinary bladder (urothelium/lamina propria). MATERIALS AND METHODS The responses of isolated strips of porcine urothelium/lamina propria to noradrenaline, phenylephrine, and isoprenaline were obtained in the absence and presence of receptor subtype-selective antagonists. Quantitative reverse-transcriptase polymerase chain reaction was undertaken to assess the expression of adrenoceptor genes. RESULTS The tissues expressed all α1- and β-adrenoceptor subtypes, with the α1A-, α1B-, and β2-adrenoceptors the predominant receptors at the messenger RNA level. In the functional experiments, the rate of phasic contractions and the basal tension were increased by the α1-adrenoceptor agonists phenylephrine (100 μM) and A61603 (10 μM). The rate and tension responses to phenylephrine were reduced by low concentrations of tamsulosin (3 nM) and RS100329 (10 nM) but were unaffected by BMY7378 (100 nM), prazosin (10 nM), and RS17053 (1 μM). In contrast, isoprenaline and salbutamol (both 1 μM) induced a relaxation of tissues and slowing of phasic contractions. The rate and tension responses to isoprenaline were inhibited by propranolol (100 nM) or a combination of CGP20712A (30 nM) and ICI118551 (70 nM). The rate responses were also significantly inhibited by ICI118551 alone (70 nM). CONCLUSION Although all α1- and β-adrenoceptor subtypes were expressed in the pig urothelium/lamina propria, the α1A/L-adrenoceptor appeared to mediate increases in the contractile rate and tension. The β-adrenoceptor induced inhibition of spontaneous contractile activity appears to be predominately mediated by β2-adrenoceptors, with β1- and β2-adrenoceptors possibly involved in the tension responses.

Non-adrenergic, non-cholinergic, non-purinergic contractions of the urothelium/lamina propria of the pig bladder.

Acetylcholine, and to a lesser extent ATP, mediates neurogenic contractions of bladder smooth muscle. Recently, the urothelium and lamina propria have also been shown to have contractile properties, but the neurotransmitters involved in mediating responses to nerve stimulation have not been investigated. Isolated strips of porcine urothelium with lamina propria were electrically field stimulated and contractions recorded. Drugs interfering with neurotransmission were then employed to identify which neurotransmitters mediated responses. Strips of urothelium/lamina propria developed spontaneous contractions with a frequency of 3.5±0.1 cycles min⁻¹ and amplitude of 0.84±0.06 g. Electrical field stimulation at 5, 10, and 20 Hz resulted in frequency-related contractions (1.13±0.36 g, 1.59±0.46 g and 2.20±0.53 g, respectively, n=13), and these were reduced in the presence of tetrodotoxin (1 μm) by 77±20% at 5 Hz, 79±7% at 10 Hz and 74±12% at 20 Hz (all P<0.01), indicating they were predominantly neurogenic in nature. Neither the muscarinic antagonist atropine (10 μm), the adrenergic neurone blocker guanethidine (10 μm) nor desensitization of the purinergic receptors with α,β-methylene ATP (10 μm) affected the contractile amplitude. Similarly, responses were not affected by the nitric oxide synthase inhibitor L-NNA (100 μm) or drugs that interfere with peptide neurotransmission (capsaicin, NK2 antagonist GR159897, protease inhibitors). In conclusion, electrical depolarization of the nerves present in the porcine urothelium/lamina propria results in frequency-dependent contractions, which are predominantly neurogenic in nature. These contractions are resistant to drugs that inhibit the adrenergic, cholinergic and purinergic systems. The neurotransmitter involved in the responses of this tissue is therefore unknown but does not appear to be a peptide.

The effectiveness of virtual and augmented reality in health sciences and medical anatomy.

Although cadavers constitute the gold standard for teaching anatomy to medical and health science students, there are substantial financial, ethical, and supervisory constraints on their use. In addition, although anatomy remains one of the fundamental areas of medical education, universities have decreased the hours allocated to teaching gross anatomy in favor of applied clinical work. The release of virtual (VR) and augmented reality (AR) devices allows learning to occur through hands‐on immersive experiences. The aim of this research was to assess whether learning structural anatomy utilizing VR or AR is as effective as tablet‐based (TB) applications, and whether these modes allowed enhanced student learning, engagement and performance. Participants (n = 59) were randomly allocated to one of the three learning modes: VR, AR, or TB and completed a lesson on skull anatomy, after which they completed an anatomical knowledge assessment. Student perceptions of each learning mode and any adverse effects experienced were recorded. No significant differences were found between mean assessment scores in VR, AR, or TB. During the lessons however, VR participants were more likely to exhibit adverse effects such as headaches (25% in VR P < 0.05), dizziness (40% in VR, P < 0.001), or blurred vision (35% in VR, P < 0.01). Both VR and AR are as valuable for teaching anatomy as tablet devices, but also promote intrinsic benefits such as increased learner immersion and engagement. These outcomes show great promise for the effective use of virtual and augmented reality as means to supplement lesson content in anatomical education. Anat Sci Educ 10: 549–559.

5‐HT2A receptor enhancement of contractile activity of the porcine urothelium and lamina propria

To examine the effect of 5‐hydroxytryptamine (5‐HT; serotonin) on the contractile properties of the urothelium and lamina propria, as a better understanding of bladder physiology might aid the development of new treatments.

Nutrition and growth: assessing the impact of regional nutritional intake on childhood development and metacarpal parameters

Measuring skeletal development throughout juvenile growth can provide a greater understanding into the health, hormonal function and genetics of children. The metacarpals have been of interest for their potential to provide insights into healthy juvenile skeletal development. This study investigated the growth patterns of developing females from isolated communities who had varied diets. Anthropometrical measurements and hand-wrist X-rays were taken of 353 juvenile females from three populations: Pari Coastal Village and Bundi Highlands Village, Papua New Guinea (PNG); and Brisbane, Australia between 1968 to 1983. Radiographs were digitized, and the length and width of the second and third metacarpals compared to each subjects height and weight. As subject heights increased, metacarpal length and width increased. However, stature and second metacarpal length indicated the strongest correlation (P<0.01), compared to third metacarpal length (P<0.01) or width. From 11 to 13 years of age, Brisbane subjects were significantly heavier and taller in comparison to subjects from PNG, and coastal females were heavier and taller than the highland females. A prominent difference between the two PNG populations was the regional intake of protein in their diets. The second metacarpal presents particularly accurate measurements when determining the height or development of a child. Nutritional intake appears to have a major influence normal childhood growth, with a potential for protein deficiency to strongly inhibit growth. Any delayed growth is particularly evident in the childs stature, as well as in the development of the metacarpal long bones of the hand.

Enhancing capillary blood collection: The influence of nicotinic acid and nonivamide.

Nicotinic acid and nonivamide are often applied topically during capillary blood collection to induce vasodilation. These molecules may have an influence on immune effector cell activity in nearby tissues. This study investigates whether the induction of flushing by nicotinic acid and nonivamide causes an inflammatory response that influences the composition of immune cells present in a capillary blood sample.