Ca(2+) influx triggered by depletion of sarcoplasmic reticulum (SR) Ca(2+) stores [mediated via store-operated Ca(2+) channels (SOCC)] was characterized in enzymatically dissociated porcine airway smooth muscle (ASM) cells. When SR Ca(2+) was depleted by either 5 microM cyclopiazonic acid or 5 mM caffeine in the absence of extracellular Ca(2+), subsequent introduction of extracellular Ca(2+) further elevated [Ca(2+)](i). SOCC was insensitive to 1 microM nifedipine- or KCl-induced changes in membrane potential. However, preexposure of cells to 100 nM-1 mM La(3+) or Ni(2+) inhibited SOCC. Exposure to ACh increased Ca(2+) influx both in the presence and absence of a depleted SR. Inhibition of inositol 1,4,5-trisphosphate (IP)-induced SR Ca(2+) release by 20 microM xestospongin D inhibited SOCC, whereas ACh-induced IP(3) production by 5 microM U-73122 had no effect. Inhibition of Ca(2+) release through ryanodine receptors (RyR) by 100 microM ryanodine also prevented Ca(2+) influx via SOCC. Qualitatively similar characteristics of SOCC-mediated Ca(2+) influx were observed with cyclopiazonic acid- vs. caffeine-induced SR Ca(2+) depletion. These data demonstrate that a Ni(2+)/La(3+)-sensitive Ca(2+) influx via SOCC in porcine ASM cells involves SR Ca(2+) release through both IP(3) and RyR channels. Additional regulation of Ca(2+) influx by agonist may be related to a receptor-operated, noncapacitative mechanism.

Neurotrophins [e.g., brain-derived neurotrophic factor (BDNF), neurotrophin 4 (NT4)], known to affect neuronal structure and function, are expressed in nonneuronal tissues including the airway. However, their function is unclear. We examined the effect of acute vs. prolonged neurotrophin exposure on regulation of airway smooth muscle (ASM) intracellular Ca(2+) concentration ([Ca(2+)](i)): sarcoplasmic reticulum (SR) Ca(2+) release and Ca(2+) influx (specifically store-operated Ca(2+) entry, SOCE). Human ASM cells were incubated for 30 min in medium (control) or 1 or 10 nM BDNF, NT3, or NT4 (acute exposure) or overnight in 1 nM BDNF, NT3, or NT4 (prolonged exposure) and imaged after loading with the Ca(2+) indicator fura-2 AM. [Ca(2+)](i) responses to ACh, histamine, bradykinin, and caffeine and SOCE following SR Ca(2+) depletion were compared across cell groups. Force measurements were performed in human bronchial strips exposed to neurotrophins. Basal [Ca(2+)](i), peak responses to all agonists, SOCE, and force responses to ACh and histamine were all significantly enhanced by both acute and prolonged BDNF exposure (smaller effect of NT4) but decreased by NT3. Inhibition of the BDNF/NT4 receptor trkB by K252a prevented enhancement of [Ca(2+)](i) responses. ASM cells showed positive immunostaining for BDNF, NT3, NT4, trkB, and trkC (NT3 receptor). These novel data demonstrate that neurotrophins influence ASM [Ca(2+)](i) and force regulation and suggest a potential role for neurotrophins in airway diseases.

Study Design. Retrospective analysis of prospectively collected data. Objective. To report the follow-up curve behaviors in different Sanders staging groups. Summary of Background Data. Vertebral body tethering (VBT) is a growth modulation technique that allows gradual spontaneous follow-up curve correction as the patient grows. There is a lack of scientific evidence regarding appropriate patient selection and timing of implantation. Methods. Patients were grouped into five as: Sanders 1, 2, 3, 4–5, and 6–7. Data were collected preoperatively, at the day before discharge, and at each follow-up. Outcome measures were pulmonary and mechanical complications, readmission, and reoperation rates. Demographic, perioperative, clinical, radiographic, and complication data were compared using Fisher–Freeman–Halton exact tests for categorical variables and Kruskal-Wallis tests for the continuous variables. Results. Thirty-one (29 F, 2 M) consecutive patients with a minimum of 12 months of follow-up were included. The mean age at surgery was 12.1 (10–14). The mean follow-up was 27.1 (12–62) months. The mean preoperative main thoracic curve magnitude was 47° ± 7.6°. For all curves, preoperative and first erect curve magnitudes, bending flexibility, and operative correction percentages were similar between groups (for all comparisons, P > 0.05). The median height gained during follow-up was different between groups (P < 0.001), which was reflected into median curve correction during follow-up. Total curve correction percentage was different between groups (P = 0.009). Four (12.9%) patients had pulmonary and six (19.4%) had mechanical complications. One (3.2%) patient required readmission and two (6.5%) required reoperation. Occurrence of pulmonary complications was similar in Sanders groups (P = 0.804), while mechanical complications and overcorrection was significantly higher in Sanders 2 patients (P = 0.002 and P = 0.018). Conclusion. Follow-up curve behavior after VBT is different in patients having different Sanders stages. Sanders 2 patients experienced more overcorrection, thus timing and/or correction should be adjusted, since Sanders 3, 4, and 5 patients displayed a lesser risk of mechanical complications. Level of Evidence: 3.

Volatile anesthetics inhibit a Ni/La-sensitive store-operated Ca(2+) influx mechanism in porcine ASM cells, which likely helps maintain anesthetic-induced bronchodilation.

([Ca 2ϩ ]o), nifedipine, and KCl (preventing Ca 2ϩ influx through L-type and SOCC channels). SOCC was then activated by reintroduction of [Ca 2ϩ ]o and characterized by several techniques. We examined cAMP effects on SOCC by activating SOCC in the presence of 1 M isoproterenol or 100 M dibutryl cAMP (cell-permeant cAMP analog), whereas we examined cGMP effects using 1,2-diolate (DETA-NO nitric oxide donor) or 100 M 8-bromoguanosine 3',5'-cyclic monophosphate (cell-permeant cGMP analog). The role of protein kinases A and G was examined by preexposure to 100 nM KT-5720 and 500 nM KT-5823, respectively. SOCC-mediated Ca 2ϩ influx was dependent on the extent of SR Ca 2ϩ depletion, sensitive to Ni 2ϩ and La 3ϩ , but not inhibitors of voltage-gated influx channels. cAMP as well as cGMP potently inhibited Ca 2ϩ influx, predominantly via their respective protein kinases. Additionally, cAMP cross-activation of protein kinase G contributed to SOCC inhibition. These data demonstrate that a Ni 2ϩ /La 3ϩ -sensitive Ca 2ϩ influx in ASM triggered by SR Ca 2ϩ depletion is inhibited by cAMP and cGMP via a protein kinase mechanism. Such inhibition may play a role in the bronchodilatory response of ASM to clinically relevant drugs (e.g., ␤-agonists vs. nitric oxide).capacitative calcium entry; trachea; adenosine 3Ј,5Ј-cyclic monophosphate; guanosine 3Ј,5Ј-cyclic monophosphate; nitric oxide; isoproterenol AIRWAY SMOOTH MUSCLE (ASM) tone represents a balance between bronchoconstriction and bronchodilation. The goal of clinical therapy for pathophysiological states such as asthma, allergy, and inflammation is to prevent excessive bronchoconstriction, both in the acute and chronic setting, and to restore a balance by producing bronchodilation. Cytosolic (intracellular) Ca 2ϩ concentration ([Ca 2ϩ ] i ) is a key determinant of ASM tone (12,23,33 The cyclic nucleotides cyclic adenosine 3Ј,5Ј-cyclic monophosphate (cAMP) and cyclic guanosine 3Ј,5Ј-cyclic monophosphate (cGMP) mediate the effects of a variety of endogenous substances as well as clinically relevant drugs, e.g., ␤ 2 -agonists and nitric oxide (NO), used to produce relaxation of ASM (13,25,28). Cyclic nucleotide effects are mediated in part by downregulation of mechanisms that would normally elevate [Ca 2ϩ ] i in ASM. Previously, we demonstrated that salbutamol, a ␤ 2 -agonist (28), as well as NO donors (26) inhibit ACh-induced [Ca 2ϩ ] i oscillations in ASM that occur via repetitive SR Ca 2ϩ release and reuptake. Both cAMP and cGMP also influence the plasma membrane via membrane hyperpolarization (9, 15) and inhibition of Ca 2ϩ influx via L-type Ca 2ϩ channels (16,17). Given the relative novelty but somewhat ubiquitous expression of SOCC, there is currently limited and sometimes inconsistent data on cyclic nucleotide modulation of Ca 2ϩ influx via this mechanism in tissues other than ASM. In rat aorta, cAMP inhibits SOCC (34) but enhances it in astrocytes (37). We hypothesize that cyclic nucleotides inhibit SOCC, preventing [Ca 2ϩ ] i elevation as well as S...

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These data indicate that volatile anesthetics prevent sarcoplasmic reticulum refilling by inhibiting SOCE and enhancing cyclic nucleotide blunting of Ca influx in ASM. Such interactions likely result in substantial airway relaxation in the presence of both anesthetics and bronchodilatory agents such as beta agonists or nitric oxide.

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