scholarly journals Characterization of a novel .ALPHA.1-adrenoceptor antagonist, SGB-1534, in contractile response of isolated canine arterial and venous smooth muscle to exogenous noradrenaline: Comparison with prazosin, phentolamine and yohimbine.

1989 ◽  
Vol 50 (2) ◽  
pp. 185-193 ◽  
Author(s):  
Takaki KOGA ◽  
Yasuyuki SHIRAKI ◽  
Kazushige SAKAI
Keyword(s):  
Smooth Muscle ◽  
Contractile Response ◽  
Adrenoceptor Antagonist

Prejunctional alpha 2-adrenoceptors inhibit acetylcholine release from cholinergic nerves in equine airways

1993 ◽  
Vol 265 (6) ◽  
pp. L565-L570 ◽  
Author(s):  
M. Yu ◽  
Z. Wang ◽  
N. E. Robinson
Keyword(s):  
Smooth Muscle ◽  
Airway Smooth Muscle ◽  
Contractile Response ◽  
Electrical Field Stimulation ◽  
Cholinergic Nerves ◽  
Ach Release ◽  
Experimental Conditions ◽  
Adrenoceptor Antagonist ◽  
Cholinergic Neurotransmission ◽  
And Function

To determine the presence and function of alpha 2-adrenoceptors on cholinergic nerves innervating horse airway smooth muscle, the effects of some alpha 2-adrenoceptor agents on contractions of and acetylcholine (ACh) release from equine airway smooth muscle preparations were studied. Muscle contractions were elicited by either electrical field stimulation (EFS) or exogenous ACh. ACh release was induced by EFS and measured by high-pressure liquid chromatography and electrochemical detection. The alpha 2-adrenoceptor agonists clonidine (10(-7) to 10(-5) M) and UK-14,304 (10(-8) to 10(-6) M) concentration dependently inhibited ACh release and the contractile response to EFS but not the response to exogenous ACh. This inhibition was attenuated by the alpha 2-adrenoceptor antagonists yohimbine and idazoxan but not by the alpha 1-adrenoceptor antagonist prazosin. These results indicate that alpha 2-adrenoceptors exist on cholinergic nerves innervating equine airway smooth muscle, and activation of these receptors inhibits cholinergic neurotransmission. The observation that yohimbine alone had little effect on the contractile response to EFS suggests that, under these experimental conditions, endogenous norepinephrine had no influence on tracheal cholinergic neurotransmission via prejunctional alpha 2-adrenoceptors.

scholarly journals Characterization of adenylyl cyclase isoforms in rat peripheral pulmonary arteries

2001 ◽  
Vol 280 (6) ◽  
pp. L1359-L1369 ◽  
Author(s):  
Karen B. Jourdan ◽  
Nicola A. Mason ◽  
Lu Long ◽  
Peter G. Philips ◽  
Martin R. Wilkins ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Adenylyl Cyclase ◽  
Pulmonary Arteries ◽  
Bronchial Epithelium ◽  
Rt Pcr ◽  
Bronchial Smooth Muscle ◽  
Functional Studies ◽  
Kinase C ◽  
Rat Lungs

Activation of adenylyl cyclase (AC), of which there are 10 diversely regulated isoforms, is important in regulating pulmonary vascular tone and remodeling. Immunohistochemistry in rat lungs demonstrated that AC2, AC3, and AC5/6 predominated in vascular and bronchial smooth muscle. Isoforms 1, 4, 7, and 8 localized to the bronchial epithelium. Exposure of animals to hypoxia did not change the pattern of isoform expression. RT-PCR confirmed mRNA expression of AC2, AC3, AC5, and AC6 and demonstrated AC7 and AC8 transcripts in smooth muscle. Western blotting confirmed the presence of AC2, AC3, and AC5/6 proteins. Functional studies provided evidence of cAMP regulation by Ca2+ and protein kinase C-activated but not Gi-inhibited pathways, supporting a role for AC2 and a Ca2+-stimulated isoform, AC8. However, NKH-477, an AC5-selective activator, was more potent than forskolin in elevating cAMP and inhibiting serum-stimulated [3H]thymidine incorporation, supporting the presence of AC5. These studies demonstrate differential expression of AC isoforms in rat lungs and provide evidence that AC2, AC5, and AC8 are functionally important in cAMP regulation and growth pathways in pulmonary artery myocytes.

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