Effects of calmidazolium and dibutyryl cyclic AMP on the longitudinal internal resistance in sinus node strips.
The effects of calmidazolium (10(-7) mol/l) and db cAMP (10(-3) mol/l) on the longitudinal internal resistance (ri) in the rabbit sinus node strips were studied by means of microelectrode and extracellular recording techniques. Calmidazolium (CDZ) decreased ri by 27%. An addition of db cAMP to the CDZ-containing Tyrode potentiated this effect by further 14%. db cAMP initially decreased ri by 17%, then it enhanced this resistance by 7% above the pretreatment control value. An addition of CDZ to the db cAMP-containing Tyrode reduced ri by 41% below the pretreatment control. Possible mechanisms underlying these effects were discussed in terms of cAMP, Cai, and calmodulin action on the cell coupling.
Tuganowski
W
W
Department of Physiology, Silesian School of Medicine, Katowice, Poland.
Korczyńska
I
I
Wasik
K
K
Piatek
G
G
D000818:Animals; D003994:Bucladesine / Q000494:pharmacology*; D002450:Cell Communication / Q000187:drug effects*; D002462:Cell Membrane / Q000187:drug effects / Q000502:physiology; D004553:Electric Conductivity; D004791:Enzyme Inhibitors / Q000494:pharmacology*; D007093:Imidazoles / Q000494:pharmacology*; D008564:Membrane Potentials / Q000187:drug effects; D011817:Rabbits; D012849:Sinoatrial Node / Q000166:cytology / Q000187:drug effects / Q000502:physiology*
D004791:Enzyme Inhibitors; D007093:Imidazoles; C031938:calmidazolium; D003994:Bucladesine