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PubMed1991

Binding of radioiodinated SPECT ligands to transfected cell membranes expressing single muscarinic receptor subtypes.

The equilibrium dissociation constant and the kinetic rate constants were determined for the binding of (R)-[3H]3-quinuclidinyl benzilate ([3H]QNB) and [125I]3-quinuclidinyl-4-iodobenzilate ((R,R)- and (R,S)-[125I]IQNB) to transfected cell membranes expressing one single muscarinic acetylcholine receptor (mAChR) subtype. The association and dissociation kinetics for the m2 subtype were more rapid than for the m1 and m3 subtypes. The differential kinetic properties may be useful for the single photon emission computed tomographic (SPECT) evaluation of regional mAChR subtype alterations in disease states.

Animals↗

PubMed1986

Accumulations of cyclic AMP and inositol phosphates in guinea pig cerebral cortical synaptoneurosomes: enhancement by agents acting at sodium channels.

Activation of alpha 1-adrenergic receptors by norepinephrine in guinea pig cortical synaptoneurosomes augments accumulations of cyclic AMP elicited by 2-chloroadenosine and concomitantly increases formation of inositol phosphates. Various agents that affect calcium channels or sites of action of calcium have little or no effect on cyclic AMP accumulation elicited either with 2-chloroadenosine, or with a 2-chloroadenosine/norepinephrine combination, nor did they markedly affect formation of inositol phosphates elicited by norepinephrine. However, EGTA reduces both cyclic AMP accumulation and inositol phosphate formation. Agents such as batrachotoxin, scorpion (Leiurus) venom and pumiliotoxin B that are active at voltage-dependent sodium channels enhance accumulations of cyclic AMP and inositol phosphates. These effects are blocked by tetrodotoxin. It is proposed that enhanced influx of sodium ions increases phosphatidylinositol metabolism, resulting in formation of diacylglycerols and inositol phosphates, and that the former, through activation of protein kinase, causes an enhancement of cyclic AMP accumulations in brain tissue.

2-Chloroadenosine↗

PubMedDate not supplied

Prolapsed hyperplastic gastric polyp causing pancreatitis: case report.

A huge hyperplastic gastric polyp prolapsed into the duodenum. The compression and obstruction of the ampulla of Vater by this polyp caused acute pancreatitis. An overview of imaging findings, general considerations about hyperplastic gastric polyps, and a review of the literature are provided.

Acute Disease↗