Drugs online research references
Eur J Pharmacol. 1989 Feb 7;160(3):339-47.
Central and peripheral effects of the dihydropyridine calcium channel activator BAY K 8644 in the rat.
Bourson A, Moser PC, Gower AJ, Mir AK.
Merrell Dow Research Institute, Strasbourg, France.
Following intraperitoneal (i.p.) administration BAY K 8644 (0.5-4 mg/kg) induced an increase in blood pressure associated with bradycardia, increased tail-flick latency in response to radiant heat, decreased locomotion, induced muscle contraction, postural changes and also reduced reflex activity. Only the postural changes and reduced locomotion were seen after intracerebroventricular administration (5-20 micrograms/kg), suggesting that the other effects are mediated peripherally. All the above effects were antagonised by the calcium channel blocker nifedipine. BAY K 8644 (4 mg/kg i.p.) also significantly increased homovanillic acid and 3,4-dihydroxyphenylacetic acid concentrations in the cortex and striatum, an effect which could also be reversed by nifedipine. Apart from inducing hypotension and tachycardia, nifedipine alone had no effect on any of the above parameters. The analgesic-like activity of BAY K 8644 observed in the tail-flick test appears to be related to its vasoconstrictor effects as the peripherally acting vasodilator phenylephrine had similar analgesic activity. These results show that both central and peripheral dihydropyridine-sensitive calcium channels mediate the effects of BAY K 8644. Although a physiological role for the dihydropyridine-sensitive voltage-operated calcium channel in the CNS remains to be demonstrated, activation of these channels can clearly have functional effects.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2469593&dopt=Abstract
J Cardiovasc Pharmacol. 1989;13 Suppl 6:S13-6.
Difference between the effects of atrial natriuretic peptide and calcium antagonist on cytosolic free calcium in cultured vascular smooth muscle cells.
Takeuchi K, Abe K, Yasujima M, Sato M, Kasai Y, Tsunoda K, Hagino T, Kanazawa M, Yoshinaga K.
Second Department of Internal Medicine, Tohoku University, School of Medicine, Sendai, Japan.
The effect of atrial natriuretic peptide (ANP) on cytosolic free calcium ([Ca2+]i) was studied in monolayers of cultured vascular smooth muscle (VSM) cells loaded with a fluorescent calcium indicator, fura-2. ANP (atriopeptin III, 10(-8) M) decreased the resting level of [Ca2+]i and sustained rises in [Ca2+]i following peak levels induced by vasoconstrictive hormones (angiotensin II or vasopressin). ANP also decreased a rise in [Ca2+]i induced by high potassium (high K+) depolarization. The initial rise in [Ca2+]i induced by vasopressin was not inhibited by ANP. On the other hand, calcium antagonists (nicardipine or nifedipine) inhibited the high K+-induced rise in [Ca2+]i, whereas there was no effect on rises in [Ca2+]i induced by vasopressin. These results suggest that calcium antagonists inhibit voltage-dependent calcium channels, while ANP can decrease [Ca2+]i presumably through a stimulation of calcium-extrusion active transports in vascular smooth muscle cells.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2473340&dopt=Abstract
Am J Med. 1985 Feb 22;78(2B):35-8.
Calcium channel blocking agents in the prophylaxis of asthma.
Tinkelman DG.
Asthma is a state of reversible airway obstruction caused by the activation and response of different cell types (smooth muscle cells, mast cells, mucous gland secretory cells, and inflammatory cells) in various combinations. Recent evidence has demonstrated that all these cells require calcium-dependent reactions for their activation, which suggests that mobilization of calcium from extracellular and intraorganelle storage depots to the cytoplasmic matrix may be one possible underlying mechanism for asthma. Numerous agents have been developed to prevent this flow of calcium to the intracellular cytoplasmic matrix. Although their exact mechanism of action is not always clear, it has been shown that they can be effective in preventing muscle spasm and release of chemical mediators from mast cells following antigen and exercise challenges. Studies indicate that one calcium channel blocking agent, ketitofen, is effective as a prophylactic agent in the treatment of mild to moderate asthma. Other calcium channel blockers, including nifedipine, verapamil, and diltiazem, are now being actively investigated.
online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3976693&dopt=Abstract
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