Spontaneous myometrial contraction (SMC) in pregnant uterus is greatly related with gestational age and growing in frequency and amplitude toward the end of gestation to initiate labor. But, an accurate mechanism has not been elucidated. In human and rat uterus, all TRPCs except TRPC2 are expressed in pregnant myometrium and among them, TRPC4 are predominant throughout gestation, suggesting a possible role in regulation of SMC. Therefore, we investigated whether the TRP channel may be involved SMC evoked by mechanical stretch in pregnant myometrial strips of rat using isometric tension measurement and patch-clamp technique. In the present results, hypoosmotic cell swelling activated a potent outward rectifying current in G protein-dependent manner in rat pregnant myocyte. The current was significantly potentiated by 1microM lanthanides (a potent TRPC4/5 stimulator) and suppressed by 10microM 2-APB (TRPC4-7 inhibitor). In addition, in isometric tension experiment, SMC which was evoked by passive stretch was greatly potentiated by lanthanide (1microM) and suppressed by 2-APB (10microM), suggesting a possible involvement of TRPC4/5 channel in regulation of SMC in pregnant myometrium. These results provide a possible cellular mechanism for regulation of SMC during pregnancy and provide basic information for developing a new agent for treatment of premature labor.
Animals ; Female ; Gestational Age ; Humans ; Lanthanoid Series Elements ; Mice ; Muscle Cells ; Myometrium ; Obstetric Labor, Premature ; Osmotic Pressure ; Patch-Clamp Techniques ; Pregnancy ; Rats* ; Uterine Contraction* ; Uterus

Protease-activated receptor (PAR)-2 is expressed in endothelial cells and vascular smooth muscle cells. It plays a crucial role in regulating blood pressure via the modulation of peripheral vascular tone. Although some reports have suggested involvement of a neurogenic mechanism in PAR-2-induced hypotension, the accurate mechanism remains to be elucidated. To examine this possibility, we investigated the effect of PAR-2 activation on smooth muscle contraction evoked by electrical field stimulation (EFS) in the superior mesenteric artery. In the present study, PAR-2 agonists suppressed neurogenic contractions evoked by EFS in endothelium-denuded superior mesenteric arterial strips but did not affect contraction elicited by the external application of noradrenaline (NA). However, thrombin, a potent PAR-1 agonist, had no effect on EFS-evoked contraction. Additionally, omega-conotoxin GVIA (CgTx), a selective N-type Ca2+ channel (I(Ca-N)) blocker, significantly inhibited EFS-evoked contraction, and this blockade almost completely occluded the suppression of EFS-evoked contraction by PAR-2 agonists. Finally, PAR-2 agonists suppressed the EFS-evoked overflow of NA in endothelium-denuded rat superior mesenteric arterial strips and this suppression was nearly completely occluded by omega-CgTx. These results suggest that activation of PAR-2 may suppress peripheral sympathetic outflow by modulating activity of I(Ca-N) which are located in peripheral sympathetic nerve terminals, which results in PAR-2-induced hypotension.
Animals ; Blood Pressure ; Endothelial Cells ; Hypotension* ; Mesenteric Arteries ; Mesenteric Artery, Superior ; Muscle, Smooth ; Muscle, Smooth, Vascular ; Norepinephrine ; omega-Conotoxin GVIA ; Rats ; Receptor, PAR-2 ; Thrombin

Food-dependent exercise-induced anaphylaxis (FDEIA) is a specific variant of exercise-induced anaphylaxis that requires both vigorous physical activity and the ingestion of specific foods. In particular, it is rare occurrence for FDEIA to be associated with meat in Korea. A 15-year-old female had generalized urticaria, dyspnea, severe cough, headache, dizziness, and vomiting after singing and dancing for 1 hour and after ingesting grilled pork. Skin prick tests showed a strong positive reaction to pork, whereas the results of an oral food challenge and exercise provocation tests were negative. However, the exercise provocation test after pork ingestion showed a positive reaction manifested by generalized urticaria, cough, mild dyspnea, and a 23% decreased peak expiratory flow rate. Three allergens to pork (67 kDa, 90 kDa, and 15 kDa) reacted with the patient's serum on immunoglobulin E immunoblotting. We report a case of pork-dependent exercise-induced anaphylaxis in a patient who was sensitive to pork.
Adolescent ; Allergens ; Anaphylaxis ; Cough ; Dancing ; Dizziness ; Dyspnea ; Eating ; Female ; Food Hypersensitivity ; Headache ; Humans ; Immunoblotting ; Immunoglobulin E ; Immunoglobulins ; Korea ; Meat ; Motor Activity ; Peak Expiratory Flow Rate ; Singing ; Skin ; Urticaria ; Vomiting