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Mechanisms for the α-adrenoceptor-mediated positive inotropy in neonatal mouse ventricular myocardium were studied with isolated myocardial preparations. The phenylephrine-induced positive inotropy was suppressed by prazosin, nifedipine, and chelerythrine, a protein kinase C inhibitor, but not by SEA0400, a selective Na + /Ca 2+ exchanger inhibitor. Phenylephrine increased the L-type Ca 2+ channel current and prolonged the action potential duration, while the voltage-dependent K + channel current was not influenced. In the presence of cromakalim, an ATP-sensitive K + channel opener, the phenylephrine-induced prolongation of action potential duration, as well as the positive inotropy, were smaller than in the absence of cromakalim. These results suggest that the α-adrenoceptor-mediated positive inotropy is mediated by an increase in Ca 2+ influx through the L-type Ca 2+ channel, and the concomitant increase in action potential duration acts as an enhancing factor.

Background and Aims: Testicular sperm extraction (TESE) and intracytoplasmic sperm injection (ICSI) is an effective procedure for the treatment of male infertility, obstructive and non-obstructive azoospermia. We have reviewed our experience to investigate the correlation of TESE-ICSI with morphological, biophysical and endocrine profiles in 27 men. Results:  Testicular spermatozoa could be retrieved in 25 of 27 patients who underwent TESE. In two cases, testicular spermatozoa could not be recovered and their serum follicle-stimulating hormone (FSH) levels were significantly higher than those of the former group. However, spermatozoa could be retrieved in sufficient numbers for ICSI, even in the patient with the highest FSH concentration. Johnsen scores evaluated by diagnostic pre-TESE open biopsies were significantly higher in the cases with viable testicular spermatozoa than those in the cases without spermatozoa. However, even in the patient whose Johnsen score was 2.1, testicular spermatozoa could be retrieved with TESE, and pregnancy was achieved by ICSI. Conclusions:  The serum FSH levels and the histological findings of the testes were strong predictors for successful TESE and provided useful information for consultation and making treatment decisions on an individual case. However, whether a patient has enough spermatozoa so that an IVF procedure with ICSI is possible can only be answered by a trial TESE. (Reprod Med Biol 2003; 2 : 31-35).