Cigarette smoking is a risk factor for the development of airway hyperresponsiveness and chronic obstructive pulmonary disease. Little is known concerning the effect of cigarette smoking on the contractility of airway smooth muscle. The current study was performed to determine the responsiveness of bronchial smooth muscles isolated from rats that were subacutely exposed to mainstream cigarette ...

The importance of Ca 2 /calmodulin-dependent myosin light chain kinase (MLCK) for smooth muscle contraction is well documented.1 Until recently, myosin light chain (MLC) phosphatase was thought to be unregulated and constitutively active. However, studies have demonstrated that smooth muscle contraction is dependent on regulation of MLC phosphatase activity.2,3 The inhibition of phosphatase act...

Experiments were designed to test the hypothesis that nicotinic acetylcholine receptors (nAChRs) are present at sites of neurotransmission to the guinea pig ileum circular smooth muscle. Circular smooth muscle preparations, from which the myenteric plexus had been removed (circular muscle-axon preparation), were used for this purpose. Nicotine and dimethylphenyl piperazinium iodide (10-100 micr...

After exposure of segments of rabbit taenia coli to the nonionic detergent Triton X-100, tension could be induced by increasing the [Ca2+] in the micromolar range. In the presence of a saturating [Ca2+], this preparation developed nearly 100% of the control tetanus tension recorded from the intact muscle prior to the detergent treatment. In addition, tension could be induced by increasing the [...

The physiological relevance of smooth muscle myosin isoforms SM1 and SM2 has not been understood. In this study we generated a mouse model specifically deficient in SM2 myosin isoform but expressing SM1, using an exon-specific gene targeting strategy. The SM2 homozygous knockout (SM2(-/-)) mice died within 30 days after birth, showing pathologies including segmental distention of alimentary tra...

Agonists such as those acting at muscarinic receptors are thought to induce contraction of smooth muscle primarily through inositol 1,4,5-trisphosphate production and release of Ca(2+) from sarcoplasmic reticulum. However, the additional Ca(2+)-mobilizing messengers cyclic adenosine diphosphate ribose (cADPR) and nicotinic acid adenine dinucleotide phosphate (NAADP) may also be involved in this...