Muscarinic cholinergic regulation of L-type calcium channel in heart of embryonic mice at different developmental stages.
OBJECTIVE
To investigate the muscarinic regulation of L-type calcium current (I(Ca-L)) during development.


METHODS
The whole cell patch-clamp technique was used to record II(Ca-L) in mice embryonic cardiomyocytes at different stages (the early developmental stage, EDS; the intermediate developmental stage, IDS; and the late developmental stage, LDS). Carbachol (CCh) was used to stimulate M-receptor in the embryonic cardiomyocytes of mice.


RESULTS
The expression of I(Ca-L) density did not change in different developmental stages (P>0.05). There was no difference in the sensitivity of I(Ca-L) to CCh during development (P>0.05). This inhibitory action of CCh was mediated by inhibition of cyclic AMP since 8-bromo-cAMP completely reversed the muscarinic inhibitory action. IBMX, a non-selective inhibitor of phosphodiesterase (PDE), reversed the inhibitory action of M-receptor on I(Ca-L) current by 71.2 %+/-9.2 % (n=8) and 11.3 %+/-2.5 % (n=9) in EDS and LDS respectively. However forskolin, an agonist of adenylyl cyclase (AC), reversed the action of CCh by 14.5 %+/-3.5 % (n=5) and 82.7 %+/-10.4 % (n=7) in EDS and LDS respectively.


CONCLUSIONS
The inhibitory action of CCh on I(Ca-L) current was mediated in different pathways: in EDS, the inhibitory action of M-receptor on I(Ca-L) channel mainly depended on the stimulation of PDE. However, in LDS, the regulation by M-receptor on I(Ca-L) channel mainly depended on the inactivation of AC.
Liang
Hua-min
HM
Department of Physiology, Tongji Medical College of Huazhong University of Science and Technology, Wuhan, China.
Tang
Ming
M
Liu
Chang-jin
CJ
Luo
Hong-yan
HY
Song
Yuan-long
YL
Hu
Xin-wu
XW
Xi
Jiao-ya
JY
Gao
Lin-lin
LL
Nie
Bin
B
Li
Su-yun
SY
Lai
Ling-ling
LL
Hescheler
Juergen
J
D015056:1-Methyl-3-isobutylxanthine / Q000494:pharmacology; D015124:8-Bromo Cyclic Adenosine Monophosphate / Q000494:pharmacology; D000818:Animals; D020746:Calcium Channels, L-Type / Q000187:drug effects* / Q000378:metabolism; D002217:Carbachol / Q000494:pharmacology*; D005576:Colforsin / Q000494:pharmacology; D005260:Female; D006321:Heart / Q000196:embryology*; D051379:Mice; D018721:Muscarinic Agonists / Q000494:pharmacology*; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000502:physiology*; D018408:Patch-Clamp Techniques; D010726:Phosphodiesterase Inhibitors / Q000494:pharmacology
D020746:Calcium Channels, L-Type; D018721:Muscarinic Agonists; D010726:Phosphodiesterase Inhibitors; D005576:Colforsin; D015124:8-Bromo Cyclic Adenosine Monophosphate; D002217:Carbachol; D015056:1-Methyl-3-isobutylxanthine