Never Hypoxic Myocardial Cells

In streptozotocin diabetic male Wistar rats the activity of total nitric oxide synthase and the amount of mRNAs encoding ecNOS and iNOS depended on the duration of diabetes (Stockklau-ser-Farber et al. 2000). When diabetes had lasted for 4 to 6 weeks, both the total activity as well as the mRNA encoding ecNOS and iNOS were elevated. A decrease of NOS activity and the amounts of mRNA of ecNOS and iNOS was only seen after more than 20 weeks of diabetes. 

There is evidence that NO is involved in the chronotropic, the inotropic, and the vasodilator response to P-adrenoceptor agonists (Schmetterer et al. 1999). N -Monomethyl-L-arginine significantly blunted the human heart rate response to p-adrenoceptor stimulation by isoprenahne (0.1-0.8 pg/min) in a dose-dependent manner. 

Abundance of caveolin-3 (0.59 0.08 versus 0.20 0.08 arbitrary units, P = 0.01) but not caveo-lin-1 was increased in canine pacing-induced heart failure compared with control conditions, assessed by Western blot (Hare etal. 2000). Transmission electron microscopy revealed increased caveolae (2.7 0.4 versus 1.3 0.3) per /tm myocyte membrane P 0.005). The association between caveolin- 

The Ps adrenoceptor antagonist, BRL 37344 induced time-dependent changes of eNOS phosphorylation at Ser in isolated human cardiomyocytes of the right atrium and the left ventricle (Bloch et al. 2002). 

N -Nitro-L-arginine methylester (50 mg/kg x day) raised the blood pressure of Wistar rats by 71 % (Mandarim-de-Lacerda and Meirelles Pereira 2001). With respect to cardiomyocyte nuclear size, the angiotensin-converting enzyme inhibitor enalapril maleate (15 mg/kgxday) and the calcium channel blocker verapamil hydrochloride (15mg/kgxday) showed beneficial effects when NO synthesis was blocked. 

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Fig. 279. Prominent intramitochondrial granules in a myocardial cell between the anterior and posterior papillary muscles of the left ventricle (block 1067) of a never hypoxic rat (No. 2) treated for 7 consecutive days with intraperitoneal injection of 1.5 ml Tyrode s solution per kg body weightx day. On August 4, 1976, under pentobarbital anaesthesia (30 mg/ kg), the animal was perfused from the abdominal aorta with 2.5% glutaraldehyde in 0.1 M sodium cacodylate buffer (pH 7.4). Postfixation with 1 % osmium tetroxide in sodium cacodylate buffer. Embedded in Epon 812 and sectioned at 50 nm. Lead citrate and uranyl acetate. Plate 3320...

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