Airway smooth muscle (ASM) plays an important role in asthma pathophysiology through its contractile and proliferative functions. The cyclic nucleotides adenosine 3',5'-cyclic monophosphate (cAMP) and guanosine 3',5'-cyclic monophosphate (cGMP) are second messengers capable of mediating the effects of a variety of drugs and hormones. There is a large body of evidence to support the hypothesis t...

The present investigation was undertaken to study the effects of K+ channel openers in the relaxant responses to various agonists in estrogen primed rat uterus. Adrenaline and isoprenaline produced a dose-dependent relaxation in the estrogen primed rat uterus. The relaxant responses were found to be significantly potentiated when the preparations were exposed to PSS devoid of calcium. The respo...

Matsumoto, Tetsuya, Atsuyuki Wada, Takayoshi Tsutamoto, Tomoko Omura, Hiroshi Yokohama, Masato Ohnishi, Ichiro Nakae, Masayuki Takahashi, and Masahiko Kinoshita. Vasorelaxing effects of atrial and brain natriuretic peptides on coronary circulation in heart failure. Am. J. Physiol. 276 (Heart Circ. Physiol. 45): H1935–H1942, 1999.—Natriuretic peptide (NP) receptor has been postulated to be downr...

Previous studies have demonstrated the anti-hypertensive effects of Hibiscus sabdariffa L. (HS) in both humans and experimental animals. To explore the mechanisms of the anti-hypertensive effect of the HS, we examined the effects of a crude methanolic extract of the calyces of HS (HSE) on vascular reactivity in isolated aortas from spontaneously hypertensive rats. HSE relaxed, concentration-dep...

BACKGROUND In previous studies, the relaxant, anticholinergic (functional antagonism) and antihistaminic effects of Nigella sativa have been demonstrated on guinea pig tracheal chains. To elucidate the other mechanisms responsible for the relaxant effect of this plant, its inhibitory effect on the calcium channel was examined in this study. RESULTS The inhibitory effects of both concentration...

BACKGROUND Alkaloids extracted from lotus leaves (AELL) can relax vascular smooth muscle. However, whether AELL has a similar relaxant role on airway smooth muscle (ASM) remains unknown. This study aimed to explore the relaxant property of AELL on ASM and the underlying mechanism. METHODS Alkaloids were extracted from dried lotus leaves using the high temperature rotary evaporation extraction...

The structure-activity relationships between flavonoids and their tracheal relaxant action are little known. In the present study, 26 natural and synthetic flavonoids, divided into the five classes of flavones, flavonols, flavanones, isoflavones, and chalcones, were tested, and their IC (50) values were determined. The IC (50) values of these five classes indicated that flavones were more poten...

Isolated human bronchial muscle was stimulated to contract by carbachol, acetylcholine, and histamine. The effects of adrenaline and the alphaand beta-adrenergic blocking drugs on these contractions were then observed. Phentolamine and phenoxybenzamine potentiated the relaxant effect of adrenaline. Phenoxybenzamine alone caused relaxation of bronchial muscle and inhibited the response to the va...

Natriuretic peptide (NP) receptor has been postulated to be downregulated under a high concentration of atrial NP (ANP) in congestive heart failure (CHF), but limited information is available on how the vascular functional responsiveness to NPs is altered in coronary circulation during CHF. We assessed the relaxant effects of ANP, brain NP (BNP), and other vasodilators in isolated coronary arte...