[Clinical experience with alpha blockers and calcium antagonists in the perioperative treatment of pheochromocytoma]. / Esperienza clinica con alpha-bloccanti e calcioantagonisti nel trattamento perioperatorio del feocromocitoma.

This study aims to value the efficacy of the association between alpha-blockers and calcium channel-blockers, administered per os, in the reduction of preoperative preparation in patients with phaeochromocytoma and the calcium channel-blockers utility when are administered e.v. in the control of development of arterial paroxysmal hypertension during surgical manipulations. The trial had been conducted on 5 patients which have undergone the operation, before the operation we administered per os nifedipine and phonoxybenzamine for 8 days and during the operation we administered diltiazem e.v. The association between alpha-blockers and calcium-blockers per os, has reduced the preparation stage and has controlled the pressure parameters during the preoperative treatment. When we utilized diltiazem during the operation, we haven't note a good hemodynamic stability; these results are opposed to Tokioka's. Calcium channel-blockers and alpha-blockers seem to be a good therapy in the preoperative preparation of patients with phaeochromocytomas and they seem to be able to take fastly the standard of preoperative preparation.

Short-term preoperative treatment in a case of pheochromocytoma.

The authors show the case of a young drug addict patient with chronic hepatitis affected by pheochromocytoma, owing to his conditions, which was prepared preoperatively with a short term phenoxybenzamine i.v. We had no complications in the perioperative period. Our opinion is that it is possible, when necessary, to administer a short term therapy but this preparation isn't be considered a standard therapeutic program.

Interaction of the aminoglycoside antibiotic dihydrostreptomycin with the H+-ATPase of mitochondria.

In this paper a study is presented of the effect of dihydrostreptomycin on the H+-ATPase of the inner mitochondrial membrane. The antibiotic caused at concentrations of 1-5 X 10(-3)M a marked enhancement of the hydrolytic activity of the H+-ATPase complex in intact mitochondria and submitochondrial particles which was accompanied, in the latter, by enhancement of passive transmembrane proton conduction by the complex. The stimulation by dihydrostreptomycin of ATP hydrolysis resulted in a suppression of the sensitivity of this activity to inhibition by oligomycin. On the other hand the dihydrostreptomycin-promoted proton conduction in submitochondrial particles was suppressed by oligomycin. At concentrations above 10(-2)M dihydrostreptomycin caused inhibition of the activity of both membrane bound and isolated H+-ATPase. In submitochondrial particles devoid of the catalytic moiety (F1) of the H+-ATPase complex, dihydrostreptomycin caused partial inhibition of proton conductivity. It is concluded that the antibiotic uncouples the hydrolytic activity of the catalytic moiety (F1) from transmembrane proton conduction by the membrane sector (F0) of the ATPase complex. This effect can be followed at higher concentrations of dihydrostreptomycin by inhibition of the catalytic activity of F1 and, when F1 is removed from the membrane, by inhibition of transmembrane proton conduction by F0.

Serosal and mucosal facilitated transport of urea in urinary bladder of of Bufo bufo: evidence for an alleged water uptake.

In Bufo bufo urinary bladder an urea facilitated transport has been localised on the luminal membrane. The transport fulfils the criteria for such a mechanism, i.e. is saturable and is inhibited by phloretin, a specific inhibitor for urea transport. Similarly to that of Bufo marinus and Rana esculenta the luminal membrane of Bufo bufo urinary bladder shows an ADH stimulated facilitated transport. Experiments wtih Amphotericin B, serosal phloretin (with and without ADH), have demonstrated the presence of a facilitated urea transport localised on basolateral membrane. Urea uptake on the isolated epithelial cells of Bufo bufo urinary bladder shows a characteristic feature, different from molecules passively transported such as glycerol yet inhibited by phloretin. Allegedly with urea, water flows in to the cells by a dragging or osmotic effect.