Carbon monoxide CO, as well as nitric oxide and hydrogen sulfide, make up the family of labile biological mediators termed gasotransmitters. We hypothesized that CO may be involved in the mechanisms of regulation electrical and contractile properties of smooth muscles.The effects of carbon monoxide donor CORM II (tricarbonyldichlororuthenium(II)-dimer) on the electrical and contractile activities of smooth muscles of the guinea pig ureter were studied by the method of the double sucrose bridge. This method allows to register simultaneously the parameters of the action potential (AP) and the contraction of smooth muscle cells (SMCs), caused by an electrical stimulus.CORM II in a concentration of 10 mmol has reduced the amplitude of contractions SMCs to (86.5 ± 9.7)% (n = 6, p < 0.05), the amplitude of the AP to (88.9 ± 4.2)% (n = 6, p < 0.05) and the duration of the plateau of the AP to (91.7 ± 6.0)% (n = 6, p < 0.05). On the background of the action of biologically active substances (phenylephrine, 10 µmol or histamine, 10 µmol), these effects of CORM II amplified. The inhibitory action of СORM II on the parameters of the contractile and electrical activities of the smooth muscles of guinea pig ureter has been decreased by blocking potassium channels in membrane of SMCs by tetraethylammonium chloride (TEA) оr inhibition of soluble guanylate cyclase (ODQ [1H-[1,2,4]-oxadiazolo[4,3-a]quinoxalin-l-one]). On the background of TEA (5 mmol), a donor of CO (10 mmol) caused a reduction the amplitude of contraction SMCs to (87.0 ± 10.8)% (n = 6, p < 0.05), the amplitude of the AP to (91.7 ± 6.4)% (n = 6, p < 0.05) and the duration of the plateau of the AP to (93.4 ± 7.5)% (n = 6, p < 0.05). After the pretreatment of ODQ (1 µmol) adding CORM II (10 mmol) in solution has resulted to augment of the amplitude of contraction ureteral smooth muscle strips to (90.9 ± 4.2)% (n = 6, p < 0.05), the amplitude of the AP to (97.2 ± 10.3)% (n = 6, p < 0.05) and the duration of the plateau of the AP to and (99.7 ± 10.0)% (n = 6, p < 0.05).Thus, can be argued the inhibitory effect of carbon monoxide on the electrical and contractile activities of the guinea pig ureter SMCs is due to changes in the ionic conductivity of the membranes, above all with increasing the potassium conductance or activation of soluble guanylate cyclase.
Isolation and contractile properties of single smooth muscle cells from guinea pig taenia caeci.