Biomedical subjects

H Aoki

Publications and source records attributed to H Aoki.

779 records · Page 44Linked to original sources

PubMedDate not supplied

Participation of vasoactive intestinal polypeptide (VIP) as a humoral mediator in the erectile response of canine corpus cavernosum penis.

The ability of anti-vasoactive intestinal peptide (anti-VIP) serum to suppress the electrically induced relaxation of the corpus cavernosum was evaluated in vitro to define the role of VIP in penile erection. Strips of canine corpora cavernosa were placed in 5-ml organ chambers containing oxygenated Krebs-Ringer solution. They were stretched and fixed in place at both ends and pretreated with 2 x 10(-7)M noradrenaline (NA). NA was given to produce an optimal state of isometric smooth muscle contraction so that subsequent electrical field stimulation (EFS) could induce a good range of measurable relaxation response. This response was deemed to be an in vitro representation of penile erection. After NA treatment the cavernous tension rose markedly by 2-2.5 g; it then declined by up to 1-1.2 g upon EFS. Anti-VIP serum (1:16) or atropine sulfate (10(-6)M) was added at various time points between NA administration and EFS. When anti-VIP serum was administered, subsequent EFS-induced relaxation was attenuated by 20%-55% compared to the control EFS treatments. The degree of attenuation depended upon the frequency of EFS applied, being 20.6% +/- 4.0% at 20 Hz and 54.7% +/- 6.3% at 2 Hz. Atropine administered additionally following anti-VIP serum produced no further attenuation. However, atropine alone was capable of producing up to 23.7% +/- 3.5% attenuation. When anti-VIP serum was administered following atropine, the degree of attenuation that ensured was the sum of the attenuations produced by each of the two substances independently.(ABSTRACT TRUNCATED AT 250 WORDS)

Acetylcholine↗

PubMedDate not supplied

Involvement of vasoactive intestinal peptide (VIP) as a humoral mediator of penile erectile function in the dog.

The effects of intracorporeal infusion of anti-vasoactive intestinal peptide (anti-VIP) antisera on electrically induced penile erection were studied in 18 male mongrel dogs. Electrical pulse stimulation (4 V, 4 milliseconds, 40 Hz) of the pelvic splanchnic nerve consistently produced penile erection ("electroerection"). Using this erection model, effects of anti-VIP serum were evaluated with regard to the peak intracorporeal pressure during electroerection. Pretreatment of the animals with repetitive intracorporeal infusion of anti-VIP rabbit serum completely abolished the electroerection in nine dogs, partially suppressed it (P < 0.01) in five, and was without effects in four. In contrast, control treatment of the same 18 dogs with normal rabbit serum was totally ineffective. In six dogs in which anti-VIP serum failed to produce a complete suppression of electroerection, 0.5 mg atropine sulfate was additionally given i.v. All six dogs exhibited significant (P < 0.01) suppression of the peak intracorporeal pressure after atropine. However atropine alone did not affect the intracorporeal pressure to any significant degree. To five of these six dogs with positive response to the combination treatment with anti-VIP serum and atropine, prazosin HCl was added i.v. It was found that prazosin HCl reversed the attenuation of electroerection produced by combined anti-VIP serum and atropine. Prazosin did not affect the intracorporeal pressure when administered following anti-VIP serum. These results suggest that VIP plays a role as a humoral mediator involved in penile erection and that there is a synergistic interaction between VIP and acetylcholine. Also it appears that the effect of acetylcholine but not that of VIP is mediated by the alpha-1 adrenergic mechanism.

Animals↗

PubMedDate not supplied

Retroperitoneal lymph node dissection for testicular tumors using the thoracoabdominal approach.

During the past 4 years, 16 patients with testicular tumor underwent retroperitoneal lymph node dissection using the thoracoabdominal extraperitoneal approach described by Scardino. In 4 of them, the lymph node dissection was performed without pleurotomy using our modified technique. No uncontrollable intra- or post-complications or operative deaths occurred in our series. From our experience, it was concluded that the thoracoabdominal approach was suitable for maximum exposure of the retroperitoneal area and was associated with lower mobility. Furthermore, our modified extrapleural extraperitoneal technique also provided an excellent operative field comparable to the thoracoabdominal approach.

Adolescent↗

PubMedDate not supplied

Hemodynamic analysis of findings in patients with portal hypertension: multicenter analysis in Japan. Japan Portal Hypertension Study Group.

BACKGROUND/AIMS: A multicenter study was done to assess the pathophysiology of malcirculation with portal hypertension. PATIENTS AND METHODS: Patients were admitted to 48 different institutes from 1990 to 1992. RESULTS: Portal venous pressure was 345.9 +/- 72.1 mmH2O in patients with portal hypertension. In patients with liver cirrhosis, the diameter of the splenic artery, of the proper hepatic artery, of the left gastric artery and of the splenic vein was significantly larger (p<0.05) than seen in the controls without portal hypertension. In patients with idiopathic portal hypertension, the diameter of the splenic artery and of the vein was significantly larger (p<0.05) and that of the proper hepatic artery was significantly smaller (p<0.05) than seen in the cirrhotic patients. In the cirrhotic patients, blood flow volume was significantly larger (p<0.05) in the splenic vein. In patient with idiopathic portal hypertension, blood flow volume in the portal vein and splenic vein were significantly larger (p<0.05) and that of superior mesenteric vein showed an increasing tendency to enlarge. CONCLUSION: This study shows that a hyperdynamic state is present in patient with portal hypertension.

Case-Control Studies↗

PubMedDate not supplied

Suppressive effects of chronic hyperprolactinemia on penile erection and yawning following administration of apomorphine to pituitary-transplanted rats.

Recent studies showed in vivo and in vitro that acutely introduced prolactin (PRL) excess was capable of diminishing penile erectile function independently of the LH-testosterone (T) dynamics. In the present investigation, we examined if such independent suppressive effects can be demonstrated in the pituitary-transplant rat model with chronically elevated serum PRL. We also compared the effects of pituitary transplantation and castration on the level of erectile activity. Rats were made hyperprolactinemic by homologous transplantation of three anterior pituitaries underneath the kidney capsules, with the eutopic pituitaries left in situ. Before and 3, 5, and 8 weeks after transplant or sham surgeries, 80 micrograms/kg s.c. injection of apomorphine was given as an inducer of erection. This was followed by 30-minute observation periods during which the numbers of erections and yawning were recorded. Similar experiments were also performed with castrated rats without transplanted pituitaries. In the transplanted rats plasma PRL was markedly elevated (51.4 +/- 3.7 ng/ml) and was significantly (P < 0.001) higher than the values in the sham group (6.0 +/- 2.7 ng/ml). In contrast, plasma T was not different (P > 0.05) between the two groups. The castrated rats showed very low plasma T (0.17 +/- 0.01 ng/ml, P < 0.05 compared to the sham group) and normal PRL (P > 0.05). The numbers of both erection and yawning were significantly (P < 0.05-0.01) less in the transplant than in the sham group 8 weeks after surgeries. Castrated rats showed a significant reduction (P < 0.05) only in the numbers of erection. These results indicated that the pituitary transplantation with chronic excess of PRL and castration with T deficiency caused roughly comparable degrees of suppression of penile erectile activity through mechanisms presumably independent from one another in the rat.

Animals↗