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ATP‐sensitive K + channel activation by calcitonin gene‐related peptide and protein kinase A in pig coronary arterial smooth muscle
Author(s) -
Wellman G. C.,
Quayle J. M.,
Standen N. B.
Publication year - 1998
Publication title -
the journal of physiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.802
H-Index - 240
eISSN - 1469-7793
pISSN - 0022-3751
DOI - 10.1111/j.1469-7793.1998.117bu.x
Subject(s) - glibenclamide , protein kinase a , calcitonin gene related peptide , chemistry , cgmp dependent protein kinase , medicine , endocrinology , patch clamp , forskolin , protein kinase inhibitor , iberiotoxin , potassium channel , isoprenaline , sodium nitroprusside , biophysics , biochemistry , kinase , biology , neuropeptide , nitric oxide , mitogen activated protein kinase kinase , receptor , stimulation , diabetes mellitus
1 We used patch clamp to study whole‐cell K + currents activated by calcitonin gene‐related peptide (CGRP) in smooth muscle cells freshly dissociated from pig coronary arteries. 2 CGRP (50 n m ) activated an inward current at −60 mV in symmetrical 140 m m K + that was blocked by glibenclamide (10 μ m ), an inhibitor of ATP‐sensitive potassium (K ATP ) channels. CGRP‐induced currents were larger in cells dialysed with 0.1 m m ATP than with 3.0 m m ATP. 3 Forskolin (10 μ m ) activated a glibenclamide‐sensitive current, as did intracellular dialysis with cAMP (100 μ m ). The catalytic subunit of cAMP‐dependent protein kinase (protein kinase A, PKA), added to the pipette solution, activated equivalent currents in five out of twelve cells. 4 CGRP‐induced currents were reduced by the PKA inhibitors adenosine 3′,5′‐cyclic monophosphorothioate, R P ‐isomer, triethylammonium salt (Rp‐cAMPS; 100 μ m ) and N ‐[2‐(( p ‐bromocinnamyl)amino)ethyl]‐5‐isoquinolinesulphonamide dihydrochloride (H‐89; 1 μ m ), and abolished by inclusion of a PKA inhibitor peptide in the pipette solution. 5 The β‐adrenergic agonist isoprenaline (10 μ m ) also activated a glibenclamide‐sensitive K + current. 6 CGRP‐induced currents were unaffected by the inhibitor of cGMP‐dependent protein kinase (PKG) KT5823 (1 μ m ). Sodium nitroprusside (10 μ m ) did not activate a glibenclamide‐sensitive current in cells held at −60 mV, but did activate an outward current at +60 mV that was abolished by KT5823, or by 100 n m iberiotoxin (an inhibitor of BK Ca channels). 7 Our findings suggest that CGRP activates coronary K ATP channels through a pathway that involves adenylyl cyclase and PKA, but not PKG.