The effect of gallamine, gallopamil and nifedipine on responses to acetylcholine and carbachol in the taenia of the guinea‐pig caecum

Comparison of the effects of some muscarinic agonists on smooth muscle function and phosphatidylinositol turnover in the guinea‐pig taenia caeci

“…The tonic phase of the response to CCh was more resistant to inhibition by verapamil. Similar findings have been made with gallopamil and nifedipine (Mitchelson & Ziegler, 1984). The tonic responses to McN-A-343 and AHR-602 were inhibited by verapamil and nifedipine but also to a lesser extent than ACh; for nifedipine a four fold higher concentration of the calcium antagonist was required to produce 50% inhibition of the tonic response to the partial agonists.…”

Bay K 8644 and Acetylcholine: Different Interaction with Calcium Ions in the Rat Duodenal Muscle

“…The contractile effect of Bay K 8644 in the duode num was characterized by a slow onset, resis tance to washing, tachyphylaxis and long du ration o f action; the tachyphylaxis, however, seems to be peculiar to the duodenum since other studies performed both in the aortic muscle [7] and in isolated cells from coronary arteries [18] showed no evidence o f this phe nomenon. The different pattern of the re sponse to acetylcholine is consistent with a different mechanism at the cellular level; the involvement o f different types o f calcium channels in the acetylcholine response has been already proposed for several types of smooth muscle: there is considerable evi dence that the tonic component of the re sponse to acetylcholine is more dependent upon external calcium, whereas tightly bound sources o f Ca2+ are utilized for the phasic response [19][20][21], In contrast with ace tylcholine, Bay K 8644 enhanced both the tone and the amplitude o f rhythmic contrac tions leaving unaffected their frequency. This finding suggests that the spontaneous motil ity of rat duodenum is very sensitive to changes in Ca2+ content, and can be increased by pharmacological agents which increase Ca2+ influx into cells through voltage-oper ated channels (VOC) [19].…”

Antispasmodic and bronchodilator activities of Artemisia vulgaris are mediated through dual blockade of muscarinic receptors and calcium influx

“…The CRCs of Ca 2+ were reconstructed in the presence of different concentrations of the test material. For an investigation of competitive and non-competitive antagonism, the CCh-CRCs were constructed in the absence and presence of different concentrations of the plant extract and dicyclomine (Mitchelson and Ziegler, 1984;Jenkinson, 2002).…”