The effect of 10 mg. phentolamine intravenously on the urethral pressure profile was studied in male and female patients with lower urinary tract obstruction. A significant decrease of pressure occurred along the whole length of the urethra in both sexes, including the peak pressure zone in the male patient. This zone has been traditionally attributed to the external sphincter. It was concluded that the sympathetically innervated smooth muscle exerts a certain activity along the whole length of the proximal urethra. The phentolamine test may prove to be a useful adjunct to urethral profile studies in patients with lower urinary tract obstruction.

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We determined the relationship between bone mass and age, anthropometric variables, creatinine clearance (Ccr), and serum and urine biochemical variables in 77 normal white women (aged 41-86, mean = 67) living in their own homes. A total of 74 women were postmenopausal. Skeletal status was assessed in all subjects by x-rays of the hand with measurement of the mean combined cortical thickness (CCT) of the second metacarpal bones. In 53 women, bone mineral content of the radial shaft (RMBC) was also measured by single-photon absorptiometry (SPA) and lumbar bone mineral density (LBMD) was measured by dual-photon absorptiometry (DPA). Serum and urine biochemical variables were measured under standardized conditions on the sixth and seventh days of a controlled diet. There was a strong positive correlation between Ccr and bone mass. Although our subjects showed the expected linear decline in Ccr with age, we found that the relationship between Ccr and bone mass in the radius and lumbar spine was independent of age. On the other hand, the relationship between Ccr and CCT was not independent of age. We concluded that the relationship between Ccr and lumbar and radial bone mass is probably indicative of a relationship between glomerular filtration rate and bone mass, although this requires validation with a noncreatinine method for measurement of glomerular filtration rate. Age per se does not appear to be a cause of declining lumbar bone mass after the menopause.

We determined the relationship between bone mass and age, anthropometric variables, and serum and urine biochemical variables in 77 normal white women and 37 women with primary osteoporosis, 25 of whom had one or more vertebral compression fractures. Skeletal status was assessed by radiography of the hands with measurement of combined cortical thickness of the second metacarpal bones (CCT) or measurement of radial and lumbar bone density, or by both methods. Radial bone mineral content (RBMC) was measured by single-photon absorptiometry (SPA) and lumbar bone mineral density by dual-photon absorptiometry (DPA). Serum and urine biochemical variables were measured on days 6 and 7 of a controlled diet. In this mixed population of normal and osteoporotic women, we confirmed the strong positive correlation between creatinine clearance (Ccr) and bone mass that we previously reported in normal women. Multiple regression analysis showed that the relationship between Ccr and bone mass of the radius and lumbar spine was independent of age and body stature. Ccr was significantly lower in the 25 osteoporotic women with vertebral crush fractures than in age-matched normal women, and Ccr had predictive value for bone mass in individual subjects. The basis for the relationship between Ccr and bone mass has not been established. We excluded diminished production of 1,25-dihydroxyvitamin D as a result of declining renal function as a possible mechanism.

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