The HOCM, diatrizoate, was more toxic to rat kidneys than the LOCM iohexol; PLA2, LPO and calcium load played a role in producing renal function impairment induced by diatrizoate meglumine; amlodipine protected the renal tissue from nephrotoxicity induced by diatrizoate.

Clinical observations suggest that cigarette smoking impairs erectile function in patients with moderate arterial insufficiency. To evaluate the effects of smoking on the physiology of erection, we studied six healthy adult mongrel dogs in which bipolar cuff electrodes were implanted around the cavernous nerves. After threshold stimulation parameters for penile erection were established, cigarette smoke collected in a 60-ml. syringe was released slowly near the dog's mouth, to be inhaled by natural breathing. Stimulation of the cavernous nerve was repeated and blood samples for nicotine, cotinine and blood gases were obtained before and after each cigarette. The systolic and intracorporeal pressure, flow through the internal pudendal artery, and venous flow from the corpora cavernosa were recorded at baseline and with each electrostimulation after smoke inhalation. Five of the six dogs were unable to achieve full erection after inhalation of smoke from two to three cigarettes. Some decrease of flow through the internal pudendal artery occurred and the venous restriction ability was almost completely abolished by smoking. Further, when nicotine was injected intravenously into two additional dogs, the same phenomenon was observed. These findings support the idea that cigarette smoking may contribute to impotence in some patients.

To investigate the mechanism of drug-induced priapism, we gave the antipsychotic agent chlorpromazine and the antidepressant trazodone to 14 dogs by intravenous and intracorporeal injection. Bilateral intracorporeal pressure, blood flow within the internal pudendal artery, and systemic blood pressure were monitored. Venous outflow restriction was evaluated by continuous saline infusion of the corpus cavernosum with the infrarenal aorta clamped. When delivered by intracorporeal injection, both drugs induced erection in a manner similar to that of intracorporeal injection of papaverine. Internal pudendal arterial flow increased slightly at the beginning of tumescence, and excellent venous restriction occurred. Intravenous injection, however, could neither induce an erection nor facilitate an erection after sub-threshold neurostimulation. We believe that the alpha-adrenergic antagonist properties of chlorpromazine and trazodone probably cause priapism by local action.

To elucidate the effect of venous outflow restriction during erection, we studied eight dogs during artificial saline perfusion of the penis with and without neurostimulation to induce erection. With the infrarenal aorta clamped temporarily, saline infusion rates of 0.9 and 1.9 ml/min raised the mean intracorporeal pressure to 34 and 42 cm H2O, respectively, before stabilisation or return to baseline. When cavernous nerve stimulation was initiated, the mean intracorporeal pressure rose to 124 and 184 cm H2O (with infusion rates of 0.9 and 1.9 ml/min respectively) to induce full erection. Our results show that venous outflow restriction takes place during erection and that it is necessary not only to induce full erection but also to maintain it. Evaluation of venous competence is therefore essential during the investigation of impotence.

No abstract

To investigate the effect of chronic papaverine treatment, seven monkeys underwent repeated intracavernous injections for one year. One monkey died after 56 injections; the others received a total of 100 each. The strength and duration of erection were recorded after each injection, and the erectile tissue was examined histologically at the end of the study. Over the long term, papaverine maintains its erection-inducing capability, but it does cause pathologic changes in the erectile tissue: minimal to marked fibrosis at the injection site and hypertrophy of smooth muscle in the non-injected area of the corpus.