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Expression, activity and functional significance of inducible nitric oxide synthase in the failing human heart

^a Department of Cardiology, Medical University of Hannover, Hannover, Germany
^* Department of Pharmacology, University of Halle, Halle, Germany

View larger version (89K): [in a new window]   Figure 1 (A) NOS III mRNA (cNOS = NOS III) quantification by competitive RNA-PCR. (Top) A constant amount of total RNA was mixed with an increasing number of NOS III competitor RNA molecules, reverse transcribed into cDNA and amplified in duplicate samples by PCR (variation between duplicate samples 5%). The PCR products, indicated as angiotensin-converting enzyme target (643 bp) and NOS III competitor (518 bp), were separated by gel electrophoresis, stained with ethidium bromide and visualized by UV irridiation. On the right-hand side, a molecular weight DNA standard (M) was loaded. (Bottom) The band densities of the NOS III target and competitor DNA were evaluated using a laserdensitometer and a computer-based imaging system. The mean values of duplicate samples were plotted as logarithm of the ratio of competitor to gene target PCR products vs. the logarithm of the known number of competitor molecules. At the competition equivalence point (log ratio = 0) the original number of target mRNAs corresponds to the initial number of competitor RNA molecules used. (B) Restriction analysis of PCR NOS II products, showing specific NOS II fragments. (C) Quantification of NOS III (eNOS) and NOS II (iNOS) gene expression by competitive RT-PCR in nonfailing (NF; n = 5) and failing (CHF; n = 24) LV tissues. The number of transcripts (representing mRNA molecules per microgram total RNA) is depicted.

View larger version (11K): [in a new window]   Figure 2 Relationship between LV NOS II-(iNOS) activity and the percent increase in twitch-tension (force of contraction) induced by isoproterenol (10–7 M).

View larger version (22K): [in a new window]   Figure 3 Left ventricular tissues of patients were divided into two groups (n = 12 each) according to the median values of their NOS II-(iNOS) activity (individual data are depicted in Figure 2). (Left panel) Mean values (± SEM) for NOS II-(iNOS) activities of these two groups (statistically significant by definition). (Middle panel) Force of contraction at baseline (B) and following isoproterenol (ISO) for both groups, both absolute values and percent increase with isoproterenol are depicted. (Right panel) ß-Adrenoceptor density (Bmax) of both groups. White bars = patients with iNOS-activity > 3,120; solid bars = patients with iNOS-activity < 3,120.

View larger version (9K): [in a new window]   Figure 4 Relationship between NOS II-(iNOS) activity and the improvement of isoproterenol-induced twitch-tension (force of contraction) by L-NMMA (%). L-NMMA enhanced the isoproterenol-induced force of contraction in patients with high baseline NOS II-(iNOS) activity.

View larger version (41K): [in a new window]   Figure 5 Dose-dependent effect of the NO donor SNAP on twitch-tension (force of contraction) before and after administration of isoproterenol (10–7 M) in five muscle strip preparations from four patients. Data (mean ± SEM) are depicted in percent twitch-tension as compared to control values.