Motilin receptor expression in smooth muscle, myenteric plexus, and mucosa of human inflamed and noninflamed intestine

Introduction: Atherosclerosis is a leading cause of death in Western societies. Vasoactive peptide urotensin II (UII) is upregulated in atherosclerosis and several other cardiovascular diseases however further research is required to develop a complete understanding of UII’s role in the pathogenesis of atherosclerosis. Hypothesis: We hypothesized that UII stimulates calcification in vascular smooth muscle cells and that UII, urotensin II related peptide (URP) and UT receptor expression are upregulated in calcified aortic valves. Methods and Results: Human aortic smooth muscle cells (HASMC) were cultured in phosphate media (2.6mmol/L) for 13 days in the presence of varying concentrations of UII (0, 10, 50, 100nm) and the amount of calcium was measured with a calcium assay kit. Protein was extracted and measured with a protein assay kit. HASMC calcification was assessed as the ratio of calcium (μg)/protein (mg). HASMC calcification increased with increasing UII concentration and was significantly elevated in 100nm of UII (N=6, P<0.05) 13 days after incubation. We also examined UII, URP and UT protein expression in 90 carotid endarterectomies and 87 mitral, non-calcified and calcified aortic valves by immunohistochemistry. Multivariant Spearman correlation analyses in carotids revealed significant positive correlations between UII, URP and UT overall staining with calcification, remodeling and inflammation (P<0.05). In valves there was significant positive correlations between UII, URP and UT overall staining with calcification, fibrosis, remodeling, inflammation, lipid score and microvessels (P<0.05). Conclusion: The stimulatory effect of UII on vascular smooth muscle cell calcification as well as the upregulated expression of UII, URP and UT in calcified aortic valves suggests that the UT receptor system plays a key role in the pathogenesis of atherosclerosis and valve calcification.

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Attenuation of relaxing response induced by pituitary adenylate cyclase-activating polypeptide in bronchial smooth muscle of experimental asthma

AJP Lung Cellular and Molecular Physiology ◽

10.1152/ajplung.00315.2020 ◽

2020 ◽

Vol 319 (5) ◽

pp. L786-L793

Author(s):

Yoshihiko Chiba ◽

Chihiro Ueda ◽

Naoko Kohno ◽

Michio Yamashita ◽

Yui Miyakawa ◽

...

Keyword(s):

Smooth Muscle ◽

Airway Hyperresponsiveness ◽

Receptor Expression ◽

Rt Pcr ◽

Bronchial Smooth Muscle ◽

Binding Partner ◽

Pituitary Adenylate Cyclase ◽

Asthmatic Reaction ◽

Contraction And Relaxation ◽

Relaxing Response

Bronchomotor tone is regulated by contraction and relaxation of airway smooth muscle (ASM). A weakened ASM relaxation might be a cause of airway hyperresponsiveness (AHR), a characteristic feature of bronchial asthma. Pituitary adenylyl cyclase-activating polypeptide (PACAP) is known as a mediator that causes ASM relaxation. To date, whether or not the PACAP responsiveness is changed in asthmatic ASM is unknown. The current study examined the hypothesis that relaxation induced by PACAP is reduced in bronchial smooth muscle (BSM) of allergic asthma. The ovalbumin (OA)-sensitized mice were repeatedly challenged with aerosolized OA to induce asthmatic reaction. Twenty-four hours after the last antigen challenge, the main bronchial smooth muscle (BSM) tissues were isolated. Tension study showed a BSM hyperresponsiveness to acetylcholine in the OA-challenged mice. Both quantitative RT-PCR and immunoblot analyses revealed a significant decrease in PAC1 receptor expression in BSMs of the diseased mice. Accordingly, in the antigen-challenged group, the PACAP-induced PAC1 receptor-mediated BSM relaxation was significantly attenuated, whereas the relaxation induced by vasoactive intestinal polypeptide was not changed. These findings suggest that the relaxation induced by PACAP is impaired in BSMs of experimental asthma due to a downregulation of its binding partner PAC1 receptor. Impaired BSM responsiveness to PACAP might contribute to the AHR in asthma.

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K depletion alters angiotensin II receptor expression in vascular smooth muscle cells

AJP Cell Physiology ◽

10.1152/ajpcell.1990.258.5.c849 ◽

1990 ◽

Vol 258 (5) ◽

pp. C849-C854 ◽

Cited By ~ 53

Author(s):

S. L. Linas ◽

R. Marzec-Calvert ◽

M. E. Ullian

Keyword(s):

Smooth Muscle ◽

Angiotensin Ii ◽

Vascular Smooth Muscle ◽

Smooth Muscle Cells ◽

Vascular Smooth Muscle Cells ◽

Muscle Cells ◽

Receptor Expression ◽

Ang Ii ◽

Surface Receptors ◽

K Depletion

Dietary K depletion (KD) results in increases in the number of angiotensin II (ANG II) receptors and prevents ANG II-induced downregulation of ANG II receptors in membrane preparations of vessels from KD animals. Because dietary KD results in changes in factors other than K, we K depleted vascular smooth muscle cells (VSMC) in culture to determine the specific effects of KD on ANG II receptor expression and processing. Scatchard analysis of ANG II uptake at 4 degrees C revealed that the number of surface receptors was increased by 37% in cells in which K had been reduced by 45%. This increase also occurred in the presence of cycloheximide. To determine the effect of KD on receptor processing, we measured the number of surface receptors after exposure to ANG II in concentrations sufficient to cause down-regulation. After 30-min exposure to ANG II, the number of surface receptors was reduced by 63% in control cells but only 33% in KD cells. Thirty minutes after withdrawing ANG II, surface binding returned to basal levels in control cells but was still reduced by 20% in KD cells. To determine the functional significance of impaired receptor processing, we measured ANG II uptake at 21 degrees C. Uptake at 21 degrees C depends on the functional number of receptors, i.e., the absolute number of surface receptors and the rate at which receptors are recycled to the surface after ANG II binding. ANG II uptake at 21 degrees C was reduced by 50% in KD cells.(ABSTRACT TRUNCATED AT 250 WORDS)

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Postsynaptic enhancement by motilin of muscarinic receptor cation currents in duodenal smooth muscle

AJP Gastrointestinal and Liver Physiology ◽

10.1152/ajpgi.1998.274.3.g487 ◽

1998 ◽

Vol 274 (3) ◽

pp. G487-G492 ◽

Cited By ~ 1

Author(s):

Kazunori Yamada ◽

Hiroe Yanagida ◽

Yushi Ito ◽

Ryuji Inoue

Keyword(s):

Smooth Muscle ◽

Muscarinic Receptor ◽

Enzymatic Reactions ◽

Patch Clamp Technique ◽

Biochemical Processes ◽

Cation Current ◽

Site Of Action ◽

Cell Variant ◽

Motilin Receptor

We have investigated a potential role of motilin in amplifying the postsynaptic muscarinic responses in the rabbit duodenal smooth muscle cells, using the whole cell variant of patch-clamp technique. Stimulation of motilin receptors by exogenously applied motilin (1 nM) resulted in a large increase in carbachol (CCh)-induced atropine-sensitive cation current ( ICCh) at threshold concentrations of CCh (0.3–1 μM) at 30°C. This potentiation was abolished in the presence of a specific blocker of motilin receptor (GM109) and was attenuated with increased concentrations of either motilin or CCh, being virtually absent with maximally effective concentrations of these agonists. Motilin failed to potentiate ICChwhen the ambient temperature was reduced to 20°C or if the cation current had been directly activated by internal perfusion with guanosine 5′- O-(3-thiotriphosphate) (50 μM) bypassing the muscarinic receptor. These results suggest that some biochemical processes, such as enzymatic reactions, might be involved in the motilin-induced potentiation and that its site of action might be the muscarinic receptor and/or associated G proteins.

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