title: New biological properties of coffee melanoidins.
abstract: Water-soluble melanoidins isolated from roasted coffee induced ex vivo changes in the bioelectric and contractile activity of rat circular gastric smooth muscle tissues. They provoked a depolarization of smooth muscle cellular membranes and an increase in Ca²⁺-influx as evidenced by the increase in the frequency and amplitude of Ca²⁺-generated spike potentials. In the presence of 1 × 10⁻⁶ mol L⁻¹ acetylcholine and 1 × 10⁻⁶ mol L⁻¹ arecoline the melanoidin-evoked contraction was significantly reduced. M-cholinergic receptor blocking agents atropine, ipratropium, pirenzepine, and 4-DAMP also significantly reduced the melanoidin-provoked contraction. Nonspecific N-cholinergic receptor blockers hexamethonium and decamethonium (1 × 10⁻⁵ mol L⁻¹ each) did not influence the melanoidin-induced mechanical reaction. The melanoidins did not affect the strength of contractions evoked by adrenaline and dopamine (1 × 10⁻⁶ mol L⁻¹ each). The results obtained support the assumption that melanoidin-evoked contraction is a result of activation of muscarinic-type cholinergic receptors.
authors.affiliation: Department of Chemistry and Biochemistry, Medical University, 120 Buxton Brothers Str., 4004 Plovdiv, Bulgaria.
authors.forename: Mariana D
authors.initials: MD
authors.lastname: Argirova
authors.forename: Iliyana D
authors.initials: ID
authors.lastname: Stefanova
authors.forename: Athanas D
authors.initials: AD
authors.lastname: Krustev
mesh_terms: D000818:Animals; D002118:Calcium / Q000378:metabolism; D040503:Coffea / Q000737:chemistry / Q000378:metabolism; D003069:Coffee / Q000378:metabolism*; D006801:Humans; D009119:Muscle Contraction; D009130:Muscle, Smooth / Q000737:chemistry / Q000502:physiology; D010936:Plant Extracts / Q000378:metabolism*; D011108:Polymers / Q000378:metabolism*; D051381:Rats; D017208:Rats, Wistar; D011976:Receptors, Muscarinic / Q000378:metabolism; D013270:Stomach / Q000737:chemistry / Q000502:physiology
chemical_list: D003069:Coffee; D010936:Plant Extracts; D011108:Polymers; D011976:Receptors, Muscarinic; C011908:melanoidin polymers; D002118:Calcium