Bovine Prostate Research Articles

Photoacoustic-based sO2 estimation through excised bovine prostate tissue with interstitial light delivery

Photoacoustic (PA) imaging is capable of probing blood oxygen saturation (sO2), which has been shown to correlate with tissue hypoxia, a promising cancer biomarker. However, wavelength-dependent local fluence changes can compromise sO2 estimation accuracy in tissue. This work investigates using PA imaging with interstitial irradiation and local fluence correction to assess precision and accuracy of sO2 estimation of blood samples through ex vivo bovine prostate tissue ranging from 14% to 100% sO2. Study results for bovine blood samples at distances up to 20mm from the irradiation source show that local fluence correction improved average sO2 estimation error from 16.8% to 3.2% and maintained an average precision of 2.3% when compared to matched CO-oximeter sO2 measurements. This work demonstrates the potential for future clinical translation of using fluence-corrected and interstitially driven PA imaging to accurately and precisely assess sO2 at depth in tissue with high resolution.

波長980 nm の高出力ダイオードレーザーおよびTwister<sup>TM</sup> Large Fiber を用いた接触式前立腺蒸散術（CVP）

High power 980 nm diode laser vaporization of the prostate was introduced since 2007 to the western countries and has proven its efficiency and safety. Using TwisterTM Fiber instead of side-firing fibers, the procedure can be done in the contact manner with higher efficacy and durability. In Japan, the clinical trial for PMDA approval was performed from April 2013 and proved its safety and non-inferiority of IPSS to TURP. Since the absorption coefficients of 980 nm laser to the major chromophores of prostate (hemoglobin and water) are not so high as those of 532 nm (KTP laser or LBO laser) to hemoglobin and of 2100 nm (Ho:YAG laser) to water, the absorption depth to prostatic tissue is higher. Thus, the high efficiency of vaporization and hemostasis are assumed to be achieved when the high energy is applied. It was shown in ex vivo experiment of bovine prostate using 300W that the vaporization depth was about 3 mm and the coagulation depth was 1.2 mm after 1 sec irradiation. Clinically, the heat affected depth of prostate from urethral cavity was about 5 mm which was recognized as a low signal zone in the T2 image of MRI at two weeks after operation. Considering comparatively larger coagulation depth, on the counter side of high efficiency of vaporization and hemostasis, this modality is quite efficient and user-friendly.

Ex vivo efficacy evaluation of laser vaporization for treatment of benign prostatic hyperplasia using a 300-W high-power laser diode with a wavelength of 980 nm.

Laser vaporization of the prostate is considered to be a promising treatment for benign prostatic hyperplasia (BPH), and efficiency of vaporization and hemostasis are both important parameters for such treatment. In this study, we used a high-power laser diode with a wavelength of 980 nm to obtain high vaporization efficiency with good hemostasis. The objective of this study is to evaluate the efficacy of laser vaporization for treatment of BPH in ex vivo experiments using a 300-W high-power laser diode with a wavelength of 980 nm quantitatively. An ex vivo experimental setup simulating clinical treatment situation was constructed. Bovine prostate tissue was used as a sample. The power setting was 100, 150, 200, 250, or 300 W, and the irradiation time was 0.5, 1, or 2 s. After laser irradiation, vaporized and coagulated depths were measured. The vaporized depth increased with the laser power and irradiation time, and the results confirmed that the high-power laser diode could efficiently vaporize the prostate tissue. Coagulated depth increased as the laser power became higher. Laser vaporization of prostate tissue using a high-power laser diode with a wavelength of 980 nm represents a promising treatment for BPH; this method exhibits high vaporization efficiency and good hemostasis. However, operators must be aware of the risk of postoperative perforation of the prostatic capsule caused by coagulation of deep regions that cannot be visualized by endoscopic observation.

Optimal Laser Fiber Rotational Movement During Photoselective Vaporization of the Prostate in a BovineEx-VivoAnimal Model

Photoselective vaporization of the prostate (PVP) has emerged as an effective debulking procedure for prostatic urinary obstruction. Surgical technique for the most efficient vaporization has, however, received little scientific investigation. We used an ex-vivo bovine prostate model to investigate how variation in the angle of laser fiber rotational movement ("sweeping") affects prostate tissue vaporization efficiency. Experiments were conducted using the GreenLight™ HPS 120W laser system. A single surgeon performed a clinical PVP video analysis, forming the basis of our study design. Sixty bovine prostate specimens were vaporized using an ex-vivo chamber equipped with computer-assisted axial movements. Specimens were vaporized at a fixed sweeping speed (0.5 sweeps/sec) and variable sweeping angles (0, 15, 30, 60, 90, and 120 degrees). The volume of tissue vaporized was calculated from cross sections and compared by a two-sample t test. Clinical PVP video analysis of a single experienced surgeon showed a mean angle of 47.7 degrees with 25% of vaporization between 0 and 30 degrees. Ex-vivo analysis showed larger sweeping angles generated wider but more superficial vaporization defects, leading to smaller vaporized volumes. Specifically, vaporization volumes with angles of 0, 15, or 30 degrees were significantly greater than those with rotational angles of 45, 60, and 90 degrees (1.5-3.0 X; P<0.05). The depth of tissue coagulation significantly increased with greater rotational angles. Optimal PVP occurred at narrower angles of laser fiber sweeping in our ex-vivo model. Our findings highlight that PVP laser fiber movement can be tested in a scientific manner, identifying parameters to maximize vaporization efficiency.

Photoselective Vaporization Prostatectomy: Experience With a Novel 180 W 532 nm Lithium Triborate Laser and Fiber Delivery System in Living Dogs

We studied vaporization parameters, and anatomical and histopathological outcomes of photoselective vaporization of the prostate with the novel GreenLight™ XPS™ 180 W, 532 nm lithium triborate laser and MoXy™ fiber in a survival model of living dogs. We compared these findings with those of the existing GreenLight HPS™ 120 W 532 nm lithium triborate laser photoselective vaporization of the prostate in living dogs. Eight dogs underwent antegrade photoselective vaporization of the prostate with the 180 W laser delivered through a new 750 μm (vs the existing 600 μm core diameter), 50% larger, spot sized, side firing fiber. Four dogs were sacrificed 3 hours and 8 weeks postoperatively, respectively. We recorded laser energy and time. Prostates were sectioned, measured and histologically analyzed after hematoxylin and eosin, triphenyltetrazolium chloride or Gomori trichrome staining and compared with a normal control. Photoselective vaporization of the prostate with the 180 W laser bloodlessly created a 76% larger cavity (mean 11.8 vs 6.7 cm(3), p = 0.014), vaporized tissue at a 77% higher rate (mean 2.3 vs 1.3 cm(3) per minute, p = 0.03) and did so in 37% less time per volume vaporized (0.5 vs 0.8 minutes per cm(3), p = 0.003). Hematoxylin and eosin, and triphenyltetrazolium chloride staining histologically revealed a 33% thicker mean coagulation zone vs that of 120 W laser photoselective vaporization of the prostate (2.0 ± 0.4 vs 1.5 ± 0.3 mm, p <0.005). In prostates healed for 8 weeks postoperatively hematoxylin and eosin, and Gomori trichrome staining showed re-epithelialized cavities with negligible submucosal fibrosis compared with a normal prostate. GreenLight XPS 180 W 532 nm lithium triborate laser photoselective vaporization of the prostate with the MoXy fiber has a significantly higher vaporization rate and speed with a deeper hemostatic coagulation zone but favorable tissue interaction and healing equal to those of HPS 120 W laser photoselective vaporization of the prostate in dogs.

Quantitative Evaluation of High Power Effect on 532 nm Laser Vaporization of Bovine Prostate In Vitro

We investigated the effect of 120 to 200 W high power levels on in vitro vaporization of bovine prostate using a custom-made 532 nm lithium triborate laser system. Light (532 nm) delivered through a newly designed 750 microm core diameter side firing prototype fiber vaporized 114 bovine prostate tissue specimens in saline at 20C using a 2-dimensional scanning system. Various conditions were tested, including 120 to 200 W power, 1 to 5 mm working distance and 2 to 8 mm per second treatment speed. Regardless of treatment speed 180 W was the optimal power to maximize tissue vaporization efficiency by removing 80% more tissue than at 120 W. At 120 and 180 W laser light vaporized tissue more efficiently at a 4 mm per second treatment speed and vaporized equally efficiently at up to 3 mm working distance. At the slowest treatment speed the mean thickness of the coagulation zone at 180 W was 20% thicker than at 120 W (1.31 vs 1.09 mm) but still thin, comparable to previous findings of 1 to 2 mm. In vitro the 532 nm lithium triborate laser showed that 180 W is the optimal power to maximize tissue vaporization efficiency with enhanced coagulation characteristics. These desirable outcomes must be validated in vivo.

The Effect of Laser-Fiber Sweeping Speed on the Efficiency of Photoselective Vaporization of the Prostate in anEx VivoBovine Model

Recommendations for efficient photoselective vaporization of the prostate (PVP) include a side-to-side rotational laser-fiber "sweeping" motion, yet scientific study of this technique is lacking. We investigated whether the speed of laser-fiber sweeping affects tissue vaporization efficiency. PVP was performed using the 120-W GreenLight high-performance system. Video analysis of a surgeon performing PVP was carried out to identify sweeping speeds used clinically. PVP efficiency was subsequently tested at four different sweeping speeds using two manipulations of an ex vivo bovine prostate model, including (1) excised prostate tissues (n = 40) in a vaporization chamber equipped with motorized laser-fiber movements; (2) retrograde endoscopic vaporization (n = 80) within whole lower urinary tracts. Vaporized cavity sizes and coagulative margins were measured by liquid-paraffin molding and histologic cross-sectioning approaches. Video analysis of clinical PVP showed wide variability in sweeping speed, mostly ranging between 0.5 and 2.0 (mean 1.50) sweeps/second. Using either manipulation of the ex vivo bovine prostate model described above, PVP at lower sweeping speeds (0.5 and 1.0 sweeps/second) removed significantly more tissue (up to twofold) compared with higher sweeping speeds (1.5 and 2.0 sweeps/second), with significant albeit minimal reductions in coagulation margins. In this ex vivo prostate model, our results suggest that vaporization efficiency is compromised with faster laser-fiber sweeping. This finding counters principles of traditional transurethral resection of the prostate, in which faster axial movement toward the surgeon removes tissue more efficiently. This study highlights that PVP technique can be tested in a scientific manner, identifying optimal parameters for achieving maximal tissue vaporization efficiency.

Laser Vaporization of Bovine Prostate: A Quantitative Comparison of Potassium-Titanyl-Phosphate and Lithium Triborate Lasers

We compared the outcomes of in vitro vaporization of bovine prostate using the lithium triborate GreenLight HPS and the GreenLight KTP PV photoselective vaporization laser. A total of 96 specimens of bovine prostate tissue in saline at 20C were vaporized with a 2-dimensional scanning system using a side firing fiber emitting a 532 nm wavelength at 80 W using the KTP laser, and at 80 and 120 W using the HPS laser at a working distance of 0.5 to 5 mm and a treatment speed of 2 to 8 mm per second. Dimensions of the vaporized tissue and resultant lesions were assessed. At a minimum working distance of 0.5 mm and a treatment speed of 4 mm per second (determined by optimum vaporization volume/energy use) the HPS laser at 80 and 120 W vaporized 50% and 100% more tissue, respectively, than the KTP laser at the customary 80 W. At the same treatment speed the HPS laser vaporized equally efficiently at up to 3 mm working distance at each power level, whereas the KTP laser lost efficiency at working distances beyond 0.5 mm. The 2 lasers vaporized more tissue at slower (longer lasing) treatment speeds but even at the slowest treatment speed mean thickness of the coagulation zone with the HPS laser at 80 and 120 W was comparable to that of the 80 W KTP laser (0.80 and 1.07 mm, respectively, vs 0.81). In vitro the lithium triborate GreenLight HPS 120 W laser vaporizes bovine prostate far more efficiently than the KTP photoselective vaporization laser but coagulates it equally well. These favorable outcomes must be validated in vivo.

Effects of Zinc Compound on Body Weight and Recovery of Bone Marrow in Mice Treated with Total Body Irradiation

This study aimed to investigate if zinc compound would have effects on body weight loss and bone marrow suppression induced by total body irradiation (TBI). ICR mice were divided randomly into two groups and treated with test or control compounds. The test compound contained zinc (amino acid chelated with bovine prostate extract), and the control was reverse osmosis pure water (RO water). One week after receiving the treatment, mice were unirradiated, or irradiated with 6 or 3 Gy by 6 MV photon beams to the total body. Body weight changes were examined at regular intervals. Three and 5 weeks after the radiation, animals were sacrificed to examine the histologic changes in the bone marrow. Lower body weight in the period of 1-5 weeks after radiation and poor survival rate were found after the 6 Gy TBI, as compared with the 3 Gy groups. The median survival time after 6 Gy and 3 Gy TBI for mice given the test compound were 26 and 76 days, respectively, and the corresponding figures were 14 and 70 days, respectively, for mice given the control compound (p < 0.00001). With zinc supplement, the mean body weight in mice which received the same dose of radiation was 7-8 g heavier than in the water-supplement groups during the second and third weeks (p < 0.05). Hence, there was no statistically significant difference in survival rate between zinc and water supplement in mice given the same dose of irradiation. Histopathologically, there was less recovery of bone marrow cells in the 6 Gy groups compared with the 3 Gy groups. In the 3 Gy water-supplement group, the nucleated cells and megakaryocytes were recovered in the fifth week when recovery was still not seen in the 6 Gy group. With zinc supplement, these cells were recovered in the third week. In this study, we found that zinc is beneficial to body weight in mice treated with TBI. Histologic examination of bone marrow showed better recovery of bone marrow cells in groups of mice fed with zinc. This study suggests that zinc can be used as supplements in cancer patients receiving radiotherapy to reduce radiation-induced complications.

Identification of α-1L and α-1A Adrenoceptors in Human Prostate by Tissue Segment Binding

Silodosin (KMD-3213 or [(-)-1-(3-hydroxypropyl)-5-[(2R)-2-({2-[2-(2,2,2trifluoroethoxy)phenoxy]ethyl}amino)propyl]-2,3-dihydro-1H-indole-7-carboxamide]) (Kissei Pharmaceutical Co., Ltd., Matsumoto, Japan) is a selective antagonist for alpha-1A and alpha-1L adrenoceptors. Using this tritiated ligand the 2 alpha-1 adrenoceptors were examined in binding studies with intact tissue segments and membrane preparations of human prostate, and compared with functionally identified alpha-1 adrenoceptor. Binding assays with tissue segments and membrane preparations of human prostate samples were performed using [3H]-silodosin and binding affinities for various drugs were estimated. In functional experiments antagonist affinities were evaluated from the inhibitory potency against the contractile response to noradrenaline. [3H]-silodosin bound to intact segments and membrane preparations of human prostate with subnanomolar affinity. [3H]-silodosin binding sites in intact segments were divided into 2 distinct components with different affinities for prazosin and RS-17053 (N-[2(2-cyclopropylmethoxyphenoxy)ethyl]-5-chloro-alpha, alpha-dimethyl1H-indole-3-ethanamine hydrochloride) (Research Biochemicals International, Natick, Massachusetts), while binding in membrane preparations showed single high affinity for these drugs. [3H]-silodosin binding sites also showed high affinity for silodosin and tamsulosin but low sensitivity to BMY 7378 (8-(2-(4-(2-methoxyphenyl)-1-piperazinyl)ethyl)-8-azaspiro(4.5)decane-7,9-dione) (Research Biochemicals International) in intact segments and in membrane preparations. In functional experiments silodosin and tamsulosin potently inhibited the contractile response to noradrenaline but prazosin, RS-17053 and BMY 7378 showed low antagonistic affinity. The current binding studies in human prostate samples clearly show that alpha-1L and alpha-1A adrenoceptors coexist as pharmacologically distinct entities in intact tissues but not in crude membrane preparations. Also, alpha-1 adrenoceptors involved in the contractile response to noradrenaline are the alpha-1L subtype.

Analysis of a Regulatory Protein Isolated from the Bovine Prostate

Analysis of a Regulatory Protein Isolated from the Bovine Prostate

Tamsulosin: Assessment of Affinityof 3H-P razosin Binding to Two Alpha-1- Adrenoceptor Subtypes in the Canine Aorta

This study was performed to assess the affinity of tamsulosin to the α_1L- in addition to α_1B-adrenoceptor (α₁-AR) subtypes coexisting in the canine aorta using the radioligand binding assay. The antagonistic effects of this drug on contraction of the rat aorta were also assessed, and the results were compared with those obtained with prazosin, amosulalol, labetalol, ketanserin, clonidine and propranolol. The pKi value of tamsulosin to the α_1L-subtype was lower than those of prazosin and HV-723, but higher than those of amosulalol, ketanserin and labetalol. The pKi value of tamsulosin for the α_1B-subtype in the canine aorta was similar to that of prazosin. However, this drug showed a higher pKi value than amosulalol, HV-723, labetalol and ketanserin. On the other hand, the order of inhibition potencies for contraction of the rat aorta by phenylephrine was as follows: prazosin > tamsulosin > amosulalol > HV-723 > labetalol > ketanserin > clonidine > propranolol. Thus, although the affinity of tamsulosin to the α_1B-AR subtype in the canine aorta was as high as that in the bovine prostate reported in our previous study, the affinity (pKi 7.87) of this drug to α_1L-AR in the canine aorta was lower than that (pKi 8.99) in the bovine prostate. These observations suggested that the pharmacological potencies of tamsulosin in the aorta and prostate may be different.

Detection of illegal estrogen administration through immunohistochemical markers in the bovine prostate

The immunodetection of diverse cell markers was evaluated in prostatic samples from bullocks, and bullocks showing epithelial hyperplasia-metaplasia, with oestrogen-induced changes, and in experimental samples from bullocks inoculated with dietylstilbestrol (DES). Antigen-retrieval procedures allowed the use of tissues that had been fixed in formalin for long periods. Three tissue markers were chosen for the study: cytokeratins 13 and 16, vimentin and desmin. Monoclonal antibody K8.12 (specific for cytokeratins 13 and 16) stained basal cells and hyperplastic-metaplastic epithelium; monoclonal antivimentin, and desmin, allowed the definition of fibromuscular changes.

Tamsulosin: Assessment of Affinity of 3H-Prazosin Bindings to Two α 1-Adrenoceptor Subtypes (α 1H and α 1L) in Bovine Prostate and Rat Heart and Brain

1. The present study was designed to assess the displacement potencies of tamsulosin to 3H-prazosin bindings in two α 1-adrenoceptor (AR) subtypes (α 1H and α 1L) in bovine prostate, rat heart and brain compared with those of amosulalol, labetalol, ketanserin, clonidine and propranolol. 2. The p K i values of tamsulosin to α 1H and α 1L subtypes in bovine prostate were 9.13 and 8.99 and these values were almost the same as those of prazosin. On the other hand, low p K i binding values of amosulalol, labetalol, ketanserin, clonidine and propranolol to these subtypes were observed. 3. Low p K i values of tamsulosin to α 2- and β-ARs and muscarinic and 5HT 2 receptors in the rat brain were observed. 4. These results suggest that tamsulosin has high affinities to α 1L-AR subtypes in bovine prostate and rat hearts as well as α 1H-AR subtypes, implying an inhibitory effect of this drug on the contraction of the prostate.

Effects of bovine prostate powder on zinc, glucose, and insulin metabolism in old patients with non—insulin-dependent diabetes mellitus

Since rabbit prostate extract strongly stimulated intestinal zinc absorption and improved the diabetic condition of streptozotocin-induced diabetic rats, we examined the effects of 200 mg bovine prostate powder supplemented with 20 mg zinc (Pro-Z) on the clinical manifestations of older male patients with type II diabetes. Twenty-two male patients who received Pro-Z capsules two to four times per day for 3 months showed reduced mean fasting blood glucose levels from 202 to 169 mg/dL, hemoglobin A 1C-(HbA 1C) concentraitons from 12.2% to 9.5%, and mean values for the 3-hour area response above the fasting glucose concentration (TAFGC) from 141 to 102 mg glucose/dL/h. In eighteen patients who received placebo, mean values for fasting blood glucose decreased from 167 to 165 mg/dL and HbA 1AC from 10.4% to 10.2%, and for TAFGC increased from 121 to 126 mg glucose/dL/h. No detrimental changes occured in the liver and kidney function of patients receiving either Pro-Z or placebo. However, blood cholesterol and low-density lipoprotein in patients receiving Pro-Z decreased slightly, whereas values in the placebo group tended to increase. The mean fasting plasma insulin decreased 15.5 to 13.8 μU/mL in subjects given Pro-Z, while the zinc concentration increased from 1.21 to 1.39 μg/mL. In contrast, the mean value for plasma insulin in the placebo group changed from 14.4 to 15.4 μU/mL (worsened), and for zinc, from 1.24 to 1.30 μg/ml. Interestingly, fasting urinary glucose concentrations in subjects given Pro-Z decreased from 1,249 to 378 mg/dL, whereas in those given were normal, these results suggest that biochemical constituents in the prostate including zinc may be involved in controlling glucose metabolism in patients with non—insulin-dependent diabetes mellitus.

Immunohistochemical localization of phospholipase A 2 in human and bovine male reproductive organs

Phospholipase A 2(PLA 2) taken from human seminal plasma and purified about 1450-fold was injected into rabbits to prepare polyclonal antibodies. The antiserum produced and the IgG purified from the antiserum were used to compare the immunohistochemical localization of PLA 2 in the human male reproductive system with that in the bull. In Western blot analyses, the polyclonal antibodies cross-reacted with purified PLA 2s from human seminal plasma, bovine Cowper's glands and with partly purified PLA 2 from bovine seminal vesicle fluid. On the other hand, purified PLA 2s from Crotalus adamanteus venom, bovine pancreas or from bovine prostate were not recognized by the polyclonal antibodies. With an indirect peroxidase technique, PLA 2 was localized in the epithelial cells of the human prostate and bovine seminal vesicles as well as in the fibrous connective tissue of bovine Cowper's gland. Indirect peroxidase staining also gave an immunoreaction in the enlarged acrosomes of round spermatids in the human testis. Using an indirect immunofluorescence method, ejaculated human spermatozoa revealed an immunoreaction which was not uniform, and the reaction was restricted to the middlepiece and the acrosomal and postacrosomal regions. In conclusion, human seminal plasma, spermatozoa and prostate PLA 2s were immunohistochemically related to those from bovine Cowper's gland, seminal vesicles and seminal fluid.

Immunohistochemical study of phospholipase A2 in boyine prostate

Approximately 1,100-fold purified phospholipase A2 (PLA2) from bovine prostate was injected into rabbit to prepare polyclonal antibodies. Antibodies produced showed specific immunoprecipitation only with the purified enzyme, as well as with homogenate of bovine prostatic tissue. By Western blot analysis or by immunodiffusion test, no cross-reactivity with PLA2 purified from human seminal plasma, bovine pancreas, Crotalus adamanteus venom, or with partially purified PLA2 from bovine seminal vesicle fluid or Cowper's glands was observed. Using the indirect peroxidase technique, PLA2 was localized in the cytoplasm of bovine prostatic epithelial cells. By immunogold microscopy, this enzyme was directly visualized inside the lysosomes, as well as in the endoplasmic reticulum of the glandular epithelial cells. Enzyme activity was localized in two principal subcellular sites: the mitochondria and lysosome-enriched fraction, and in the microsomal fraction.

Purification and characterization of phospholipase A2 from bovine prostate.

Phospholipase A2 (PLA2) was purified from bovine prostate by ammonium sulphate precipitation and fractionation by anion exchange chromatography, chromatofocusing and gel filtration. The purified enzyme was Ca(2+)-dependent and had a pH-optimum of 8.0. Ba2+, Fe2+, Hg2+, Mg2+, Pb2+, Sr2+ and Zn2+ as well as lysophosphatidylcholine, lysophosphatidylethanolamine and p-bromophenacyl bromide (p-BPB) inhibited the enzyme strongly. The enzyme had an estimated molecular weight of 12,000 +/- 1,000 daltons on SDS-PAGE. Isoelectric focusing showed one PLA2 activity-containing band at pl 5.3. The purified enzyme hydrolysed linoleic acid at the sn-2 position of phosphatidylcholine and phosphatidylethanolamine with high selectivity, compared to arachidonic acid.

Alpha 1-adrenoceptor subtypes in bovine prostate.

The object of this study was to examine the existence and characteristics of alpha 1-adrenoceptor subtypes in the bovine prostate using the radioligand binding assay method. [3H]Prazosin was used as the radioligand and its binding sites in bovine prostate were classified into two subtypes. One subtype showed a high affinity (alpha 1High, Kd: 101.1 pM and Bmax: 11.8 fmol (mg protein)-1) and the other had a low affinity (alpha 1Low, Kd: 3371.4 pM and Bmax: 50.5 fmol (mg protein)-1). Although the same pKi values of clorethylclonidine, p-aminoclonidine, benoxathian and dibenamine to both alpha 1High and alpha 1Low binding sites in bovine prostate tissue were observed, other alpha 1 antagonists used in this study had different pKi values for the two alpha 1-adrenoceptor subtypes. The existence and binding characteristics of alpha 1-adrenoceptor subtypes in bovine prostate were clarified. It is possible that agents selective for one site may contribute to the development of better drugs for the treatment of bladder outlet obstructions of men with benign prostatic hyperplasia.

Binding Characteristics of .ALPHA.1-Adrenoceptors in Bovine Prostate Using a Radioligand Binding Assay.

Binding characteristics of alpha 1-adrenoceptors in the bovine prostate were examined using a radioligand binding assay. [3H]Bunazosin was used as a radioligand. The optimal incubation conditions for the radioligand binding assay were determined: incubation time (30 min), protein concentration (0.2 mg/tube) and temperature (30 degrees C). Scatchard plots for alpha 1-adrenoceptors in bovine prostates were linear and the Kd and Bmax values were 0.61 nM and 49.8 fmol/mg protein, respectively. The pKi value of terazosin was significantly higher than those of prazosin, bunazosin or phentolamine in the bovine prostate. Since this radioligand binding assay using [3H]bunazosin demonstrated the presence of alpha 1-adrenoceptors in bovine prostates, this method is useful for the assessment of alpha 1-blockers of new chemicals synthesized for the treatment of the benign prostatic hyperplasia.