Laminin acts via beta 1 integrin signalling to alter cholinergic regulation of L-type Ca(2+) current in cat atrial myocytes.
A perforated patch recording method was used to determine how plating cells on laminin (20 microg ml(-1); >2 h) alters cholinergic regulation of L-type Ca(2+) current (I(Ca,L)) in atrial myocytes. Acetylcholine (ACh; 1 microm)-induced inhibition of basal I(Ca,L) was not different between cells on glass and laminin. However, stimulation of I(Ca,L) elicited by ACh withdrawal was significantly smaller in cells on laminin (10 +/- 2 %) than on glass (48 +/- 5 %) (P < 0.001). Stimulation of I(Ca,L) induced by either spermine-NO (200 microm), milrinone (10 microm), IBMX (100 microm) or forskolin (1 microm) was significantly smaller in cells plated on laminin than on glass. However, stimulation of I(Ca,L) by 100 microm 8-CPT-cAMP or intracellular dialysis with 50 microM cAMP was not different between cells plated on laminin or glass. Basal, forskolin- and IBMX-stimulated cAMP content was significantly smaller in cells plated on laminin than on glass. Stimulation of I(Ca,L) by ACh withdrawal was significantly smaller in cells plated on an alpha beta 1-integrin antibody (10 +/- 4 %) than on glass (3 +/- 6 %; P < 0.001). In cells on laminin, prior exposure to 100 microg ml-1 YIGSR, a laminin receptor-binding peptide, restored ACh-induced stimulation of I(Ca,L) (58 +/- 14 %)laminin alone (7 +/- 2 %; P < 0. 05). Addition of 20 microm cytochalasin D or 1 microM latrunculin A, agents that prevent actin polymerization, to cells on laminin restored ACh-induced stimulation of I(Ca,L). We conclude that laminin binding to beta 1 integrins acts in association with the actin-based cytoskeleton to attenuate adenylate cyclase activity. As a result, laminin inhibits NO-mediated stimulation of I(Ca,L) elicited by ACh withdrawal. Laminin-integrin signalling may be relevant to changes in autonomic regulation that occur during cardiac development and/or disease.
Wang
Y G
YG
Department of Physiology, Stritch School of Medicine, Loyola University Chicago, Maywood, IL 60153, USA.
Samarel
A M
AM
Lipsius
S L
SL
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D000109:Acetylcholine / Q000378:metabolism* / Q000494:pharmacology; D000199:Actins / Q000378:metabolism; D000067956:Adenylyl Cyclase Inhibitors; D000262:Adenylyl Cyclases / Q000378:metabolism; D000818:Animals; D020746:Calcium Channels, L-Type / Q000187:drug effects / Q000378:metabolism*; D002415:Cats; D002478:Cells, Cultured; D005576:Colforsin / Q000494:pharmacology; D000242:Cyclic AMP / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D003599:Cytoskeleton / Q000378:metabolism; D005260:Female; D006325:Heart Atria / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019012:Integrin beta1 / Q000378:metabolism*; D007797:Laminin / Q000378:metabolism* / Q000494:pharmacology; D008297:Male; D020105:Milrinone / Q000494:pharmacology; D009206:Myocardium / Q000166:cytology / Q000378:metabolism*; D020030:Nitric Oxide Donors / Q000494:pharmacology; D009589:Nitrogen Oxides; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology; D015398:Signal Transduction / Q000187:drug effects; D013096:Spermine / Q000031:analogs & derivatives / Q000494:pharmacology; D013873:Thionucleotides / Q000494:pharmacology
D000199:Actins; D000067956:Adenylyl Cyclase Inhibitors; D020746:Calcium Channels, L-Type; D019012:Integrin beta1; D007797:Laminin; D020030:Nitric Oxide Donors; D009589:Nitrogen Oxides; D010726:Phosphodiesterase Inhibitors; D013873:Thionucleotides; C091861:spermine nitric oxide complex; D005576:Colforsin; D013096:Spermine; C015929:8-((4-chlorophenyl)thio)cyclic-3',5'-AMP; D000242:Cyclic AMP; D000262:Adenylyl Cyclases; D020105:Milrinone; D000109:Acetylcholine; D015056:1-Methyl-3-isobutylxanthine