Poly[[(N,N-dimethyl-formamide-κO)(µ(3)-pyrazine-2,3-dicarboxyl-ato-κN,O:O:O)copper(II)] monohydrate].

In the title compound, {[Cu(C(6)H(2)N(2)O(4))(C(3)H(7)NO)]·H(2)O}(n), the Cu(II) atom is coordinated by an N,O-bidentate pyrazine-2,3-dicarboxyl-ate (pzdc) dianion, two O atoms from two other pzdc anions and one O atom from the dimethlyformamide ligand, forming a distorted square-pyramidal CuNO(4) geometry. The polymeric character of the structure is established by the formation of layers parallel to (100) via bridging pzdc ligands. O-H⋯O hydrogen bonding between water mol-ecules and uncoordinated carboxyl-ate O atoms leads to additional stabilization of the structure.

Poly[aqua-[µ(2)-cis-1,2-bis-(4-pyrid-yl)ethyl-ene-κN:N'](µ(2)-5-nitro-isophthalato-κO:O',O'')nickel(II)].

In the title compound, [Ni(C(8)H(3)NO(6))(C(12)H(10)N(2))(H(2)O)](n), the Ni(II) atom is octa-hedrally coordinated by two cis N atoms from two different 1,2-bis-(4-pyrid-yl)ethyl-ene (bpe) ligands, two O atoms from one chelating carboxyl group of the 5-nitro-isophthalic acid (nip) ligand, one O atom from another monodentate nip ligand and one O atom from a water mol-ecule, forming a three-dimensional network structure. Inter-molecular O-H⋯O hydrogen bonding stabilizes this arrangement. The asymmetric unit of the structure contains one Ni(II) atom, one water mol-ecule, one nip ligand and two half-mol-ecules of the bpe ligand with an inversion centre at the mid-point of the central C=C bond.

[A simple and new type of drop recorder mainly applied in the experiment of frog heart].

AIM: To introduce the manufacture and use of a simple, new type of drop recorder of frog heart. METHODS: To improve the perfusion device of (see text for symbol) and Straub method. Two electrodes of drop recorder were fixed in an injector of 20 ml. The input tube, output tube and resistance tube were all made of plastic material. RESULTS: This device could be used to observe effects of preload, after-load, hormone and electrolyte on the cardiac output in isolated frog heart. CONCLUSION: The new type of drop recorder was economical and could be easily operated, it could be also connected to computer. Using the new type of drop recorder, effects of various physical and chemical factors on cardiac function could be observed directly, accurately.

[Electrophysiological effects of phytoestrogen genistein on guinea pig papillary muscles].

The cardiac electrophysiological effects of genistein (GST) were examined in guinea pig papillary muscle using intracellular microelectrode technique. The results obtained are as follows. (1) Duration of action potential (APD) in normal papillary muscles was decreased by GST (10 100 micromol/L) in a concentration-dependent manner. (2) In partially depolarized papillary muscles, 50 micromol/L GST not only reduced APD, but also decreased the amplitude of action potential, overshoot and maximal velocity of phase 0 depolarization. (3) Pretreatment with N( )-nitro-L-arginine (L-NNA, 5 mmol/L) failed to affect the above effects of GST (50 micromol/L)on papillary muscles. (4) 17beta-estradiol (E(2), 5 micromol/L) or GST (10 micromol/L) alone did not affect action potential, while GST combined with E(2) at the same doses shortened APD significantly. All these results indicate that the effects of GST on papillary muscles are likely due to a decrease of calcium inflow which is not mediated by NO and that GST has a facilitative or synergetic action with E(2).

Electrophysiological effects of phytoestrogen genistein on pacemaker cells in sinoatrial nodes of rabbits.

AIM: To study the electrophysiological effects of genistein (GST) on pacemaker cells in sinoatrial (SA) nodes of rabbits. METHODS: Parameters of action potential (AP) in SA node were recorded using intracellular microelectrode technique. RESULTS: GST (10 - 150 micromol/L) not only decreased the amplitude of action potential (APA), maximal rate of depolarization (Vmax) [from (6.2 +/- 2.8) to (2.8 +/- 1.4) V/s, P < 0.01], velocity of diastolic (phase 4) depolarization (VDD) [from (55 +/- 14) to (38 +/- 8) mV/s, P < 0.01], and rate of pacemaker firing (RPF) [from (154 +/- 23) to (107 +/- 25) beat/min, P < 0.01], but also prolonged duration of 90 % repolarization of action potential (APD90) in a concentration-dependent manner. Both elevation of calcium concentration (5 mmol/L) in superfusate and application of L-type Ca2+ channel agonist Bay K8644 (0.5 micromol/L) reversed the inhibitory effects of GST on pacemaker cells, while pretreatment with NG-nitro-L-arginine methyl ester (L-NAME, 1 mmol/L), an NO synthase inhibitor, failed to block the electrophysiological effects of GST. CONCLUSION: GST exerted a negative chronotropic action and induced a delayed repolarization of pacemaker cells in SA nodes of rabbits. These effects were likely due to reduction in calcium influx and potassium efflux, but had no association with NO release.

[Effects of 50 Hz-filter circuit on cardiac action potential recording and analyzing].

AIM: To study the effects of the 50 Hz-filter circuit in a microelectrode amplifier on cardiac action potential waveform and parameters. METHODS: Cardiac action potential signals were fed into a microcomputer through a glass microelectrode, a microelectrode amplifier, a differentiator and A/D converter. The cardiac action potential signals were recorded and analyzed with 50 Hz-filter circuit and without it, and the frequency spectrum in the signals was analyzed with the fast Fourier transformation. RESULTS: When the 50 Hz-filter circuit was used, the phase 0 of the potential waveform was seriously distorted and prolonged. The maximal rate of depolarization at the phase 0 was cut down, while the other parameters were not effected. CONCLUSION: There has already been much 50 Hz element in the action potential waveform. During amplifying the cardiac action potential signal, the 50 Hz-filter circuit should not be turned on. Otherwise, the experiment results will be effected.