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Biocell ; 36(2): 73-81, Aug. 2012. graf, tab
Article in English | LILACS | ID: lil-662144


After depletion of intracellular Ca2+ stores the capacitative response triggers an extracellular Ca2+ influx through store-operated channels (SOCs) which refills these stores. Our objective was to explore if human umbilical artery smooth muscle presented this response and if it was involved in the mechanism of serotonin- and histamine-induced contractions. Intracellular Ca2+ depletion by a Ca2+-free extracellular solution followed by Ca2+ readdition produced a contraction in artery rings which was inhibited by the blocker of Orai and TRPC channels 2-aminoethoxydiphenyl borate (2-APB), suggesting a capacitative response. In presence of 2-APB the magnitude of a second paired contraction by serotonin or histamine was significantly less than a first one, likely because 2-APB inhibited store refilling by capacitative Ca2+ entry. 2-APB inhibition of sarcoplasmic reticulum Ca2+ release was excluded because this blocker did not affect serotonin force development in a Ca2+-free solution. The PCR technique showed the presence of mRNAs for STIM proteins (1 and 2), for Orai proteins (1, 2 and 3) and for TRPC channels (subtypes 1, 3, 4 and 6) in the smooth muscle of the human umbilical artery. Hence, this artery presents a capacitative contractile response triggered by stimulation with physiological vasoconstrictors and expresses mRNAs for proteins and channels previously identified as SOCs.

Humans , Boron Compounds/pharmacology , Muscle Contraction/drug effects , Muscle, Smooth/drug effects , Muscle, Smooth/metabolism , RNA, Messenger/genetics , Umbilical Arteries/drug effects , Vascular Capacitance/drug effects , Blotting, Western , Cells, Cultured , Calcium Channel Blockers/pharmacology , Calcium Channels/chemistry , Calcium Channels/genetics , Calcium Channels/metabolism , Calcium/metabolism , Histamine Agonists/pharmacology , Histamine/pharmacology , Membrane Proteins/genetics , Membrane Proteins/metabolism , Muscle, Smooth/cytology , Neoplasm Proteins/genetics , Neoplasm Proteins/metabolism , Real-Time Polymerase Chain Reaction , Reverse Transcriptase Polymerase Chain Reaction , Sarcoplasmic Reticulum/drug effects , Sarcoplasmic Reticulum/metabolism , Serotonin Receptor Agonists/pharmacology , Serotonin/pharmacology , TRPC Cation Channels/genetics , TRPC Cation Channels/metabolism , Umbilical Arteries/cytology , Umbilical Arteries/metabolism
Braz. j. med. biol. res ; 44(6): 562-572, June 2011. ilus, tab
Article in English | LILACS | ID: lil-589981


Inhibition of type-5 phosphodiesterase by sildenafil decreases capacitative Ca2+ entry mediated by transient receptor potential proteins (TRPs) in the pulmonary artery. These families of channels, especially the canonical TRP (TRPC) subfamily, may be involved in the development of bronchial hyperresponsiveness, a hallmark of asthma. In the present study, we evaluated i) the effects of sildenafil on tracheal rings of rats subjected to antigen challenge, ii) whether the extent of TRPC gene expression may be modified by antigen challenge, and iii) whether inhibition of type-5 phosphodiesterase (PDE5) may alter TRPC gene expression after antigen challenge. Sildenafil (0.1 µM to 0.6 mM) fully relaxed carbachol-induced contractions in isolated tracheal rings prepared from naive male Wistar rats (250-300 g) by activating the NO-cGMP-K+ channel pathway. Rats sensitized to antigen by intraperitoneal injections of ovalbumin were subjected to antigen challenge by ovalbumin inhalation, and their tracheal rings were used to study the effects of sildenafil, which more effectively inhibited contractions induced by either carbachol (10 µM) or extracellular Ca2+ restoration after thapsigargin (1 µM) treatment. Antigen challenge increased the expression of the TRPC1 and TRPC4 genes but not the expression of the TRPC5 and TRPC6 genes. Applied before the antigen challenge, sildenafil increased the gene expression, which was evaluated by RT-PCR, of TRPC1 and TRPC6, decreased TRPC5 expression, and was inert against TRPC4. Thus, we conclude that PDE5 inhibition is involved in the development of an airway hyperresponsive phenotype in rats after antigen challenge by altering TRPC gene expression.

Animals , Male , Rats , Calcium Channels/drug effects , Carbachol/pharmacology , Piperazines/pharmacology , Sulfones/pharmacology , TRPC Cation Channels/drug effects , Trachea/drug effects , Vasodilator Agents/pharmacology , Calcium Channels/metabolism , Carbachol/antagonists & inhibitors , Gene Expression , Lactones/pharmacology , Muscle Contraction/drug effects , Muscle Contraction/physiology , Nitric Oxide/metabolism , Ovalbumin/pharmacology , Purines/pharmacology , Rats, Wistar , Sesquiterpenes/pharmacology , TRPC Cation Channels/genetics , TRPC Cation Channels/metabolism , Trachea/metabolism , Trachea/physiopathology
Article in English | WPRIM | ID: wpr-162255


During membrane depolarization associated with skeletal excitation-contraction (EC) coupling, dihydropyridine receptor [DHPR, a L-type Ca2+ channel in the transverse (t)-tubule membrane] undergoes conformational changes that are transmitted to ryanodine receptor 1 [RyR1, an internal Ca2+-release channel in the sarcoplasmic reticulum (SR) membrane] causing Ca2+ release from the SR. Canonical-type transient receptor potential cation channel 3 (TRPC3), an extracellular Ca2+-entry channel in the t-tubule and plasma membrane, is required for full-gain of skeletal EC coupling. To examine additional role(s) for TRPC3 in skeletal muscle other than mediation of EC coupling, in the present study, we created a stable myoblast line with reduced TRPC3 expression and without alpha1SDHPR (MDG/TRPC3 KD myoblast) by knock-down of TRPC3 in alpha1SDHPR-null muscular dysgenic (MDG) myoblasts using retrovirus-delivered small interference RNAs in order to eliminate any DHPR-associated EC coupling-related events. Unlike wild-type or alpha1SDHPR-null MDG myoblasts, MDG/TRPC3 KD myoblasts exhibited dramatic changes in cellular morphology (e.g., unusual expansion of both cell volume and the plasma membrane, and multi-nuclei) and failed to differentiate into myotubes possibly due to increased Ca2+ content in the SR. These results suggest that TRPC3 plays an important role in the maintenance of skeletal muscle myoblasts and myotubes.

Animals , Calcium/metabolism , Calcium Channels/metabolism , Calcium Channels, L-Type/genetics , Cations/metabolism , Cell Differentiation , Cell Proliferation , Cells, Cultured , Excitation Contraction Coupling , Gene Knockdown Techniques , Membrane Potentials , Mice , Muscle Fibers, Skeletal/metabolism , Muscle Proteins/metabolism , Myoblasts, Skeletal/metabolism , Ryanodine Receptor Calcium Release Channel/metabolism , Sarcoplasmic Reticulum/physiology , Synaptophysin/metabolism , TRPC Cation Channels/genetics , Transient Receptor Potential Channels/metabolism