Responsiveness of peripheral veins to vasodilators and the effect of nifedipine on alpha-adrenergic responsiveness in hypertension.

Vasodilators have varying hemodynamic properties that may be important in determining their efficacy for different disorders. We used the dorsal hand vein technique to measure the effects of several vasodilators infused locally and to measure the action of systemically administered nifedipine. The venodilatory effects of hydralazine, verapamil, diazoxide, and nitroglycerin were determined in peripheral veins of healthy subjects. The potency (ED50, the dose producing half-maximal response) was as follows: nitroglycerin (0.0007 micrograms/min) greater than verapamil (6.5 micrograms/min) greater than diazoxide (75 micrograms/min) greater than hydralazine (660 micrograms/min). The effect of oral nifedipine on alpha-adrenergic responsiveness of hand veins was determined. Nifedipine given in therapeutic doses for the treatment of hypertension was associated with a threefold increase in the ED50 for phenylephrine (92 to 277 ng/min; p less than 0.05) and norepinephrine (2.9 to 11.5 ng/min; p less than 0.05). Therapeutic doses of nifedipine are associated with measurable shifts in the dose-response curves to these two alpha-adrenergic agonists in the hand vein. The hand vein technique can be used not only to compare the potency of locally infused drugs but also to measure venous effects of vasoactive drugs at therapeutic concentrations achieved after systemic administration.

[Treatment of prolactin-secreting pituitary tumors with bromocriptine].

9 women and 6 men with prolactin-secreting pituitary tumors--prolactinomas (mean age 41 years, range 28-57), were treated conservatively with bromocriptine. The women usually presented with galactorrhea, menstrual disorders and headaches, and the men with headaches, decreased libido or impotence, and visual abnormalities. The symptoms had lasted from several months to 20 years, but were not correlated with tumor size. Between 77-100% of symptoms improved during bromocriptine. Prolactin levels, which correlated with the size of the tumor, averaged 1241 ng/ml before treatment and became normal in 80% of the patients. Tumor size decreased in 58% of those with macroprolactinomas. Lesions of decreased density were found in another 17% of the patients. Side-effects of bromocriptine were minor and disappeared despite continuation of therapy. The results of this series, as well as those of others, indicate that bromocriptine is the treatment of choice for micro- and macroprolactinomas.

Spontaneous pneumopericardium: case report and review of the literature.

An 84-year-old man presented with acute dyspnea and chest pain attributed to his long medical history of cardiorespiratory problems. Admission chest roentgenogram revealed a moderate pneumopericardium and a cavitary lesion in the base of the right lung. The lesion was found to be a bronchogenic carcinoma perforating through the upper pericardium to form a bronchopericardial fistula, confirmed by autopsy. A review of the literature concerning the various causes of pneumopericardium, the clinical features and the principles of treatment is included.

Absence of age-related changes in venous responsiveness to nitroglycerin in vivo in humans.

We have previously demonstrated a progressive loss in the ability of the beta-receptor agonist isoproterenol to relax veins with increasing age. In this study the influence of age on the responsiveness of medium-sized veins to local infusions of nitroglycerin was studied in two groups of 15 healthy male volunteers using the dorsal hand vein compliance technique. A dorsal hand vein was preconstricted with submaximally effective doses of phenylephrine and a dose-response curve with nitroglycerin was established. The nitroglycerin dose that caused a 50% venodilation ranged from 0.7 to 22.4 ng/min (geometric mean 3.6 ng/min) in the younger group (aged 19 to 29 years; mean +/- SD 23 +/- 3 years) and from 0.2 to 17.9 ng/min (geometric mean 3.6 ng/min) in the older subjects (aged 50 to 74 years; mean +/- SD 63 +/- 7 years) (P = 0.49 between geometric means). The mean (+/- SD) maximal venodilation, based on the pretreatment baseline, was 103% +/- 65% in the younger and 125% +/- 64% in the older subjects (P = 0.18). These results indicate that there is no age-related change in venous responsiveness to nitroglycerin.