The influence of catecholamines and serotonin on histamine uptake and metabolism by guinea pig atrium.

The influence of serotonin and catecholamines on the uptake and metabolism of 14C-histamine by isolated guinea pig atrium has been investigated. Epinephrine, norepinephrine and serotonin were found to reduce the histamine uptake and the formation of methylhistamine, in a dose-dependent fashion. The order of potency was epinephrine greater than norepinephrine greater than serotonin. Aliphatic diamines, such as spermine, do not affect the accumulation and metabolism of histamine. It is suggested that serotonin and catecholamines, may enhance histamine responses by decreasing the uptake and metabolism of this amine.     

Surgical treatment of rectourethral fistulae

9 male patients with rectourethral fistula were treated. Fistulae were congenital in 1 case, iatrogenic in 6 cases and traumatic in 2 cases. In 8 cases we used an abdominoperineal approach with omentoplasty or peritoneal flap; in 1 case a perineal approach was made. In 2 cases it was also necessary to use a transpubic approach to the posterior urethra. Good results were obtained in all cases. The importance of a proper radiological investigation of the fistulous tract and the use of omentoplasty are both emphasized.     

Cardiac electrophysiologic effects of a new calcium antagonist, lacidipine.

Lacidipine is a new 1,4-dihydropyridine derivative with potent and long-lasting antihypertensive activity. We used intracellular microelectrodes to characterize the electrophysiologic properties of lacidipine on different cardiac preparations. Lacidipine (10(-8) -10(-6) M) dose-dependently decreased contractility of driven sheep Purkinje fibers. For concentrations less than or equal to 10(-7) M, this effect was associated with a selective decrease of the plateau height. Higher concentrations (3 X 10(-7) and 10(-6) M), however, affected action potential amplitude, overshoot, and maximum rate of depolarization. In the same range of concentrations, lacidipine did not affect normal automaticity of guinea-pig sinus node and sheep Purkinje fibers. Lacidipine (10(-6) M) consistently blocked barium-induced abnormal automaticity in Purkinje fibers and reduced the amplitude and Vmax of the slow action potentials induced by histamine (10(-5) M) in guinea pig papillary muscle depolarized by potassium (22 mM). The effect of lacidipine on the slow inward current (Isi) was studied in shortened Purkinje fibers under voltage-clamp conditions. Lacidipine (10(-7)-10(-6) M) reduced the Isi without affecting the I-V relationship. None of the effects of lacidipine was reversed by 2-h washout. The results indicate that lacidipine has calcium-antagonistic properties in cardiac tissues. Its cardiac effects occur at concentrations 100 times higher than those active in the vascular smooth muscle. The lack of recovery of the lacidipine effects suggests that its interaction with the calcium channel may occur at an inner site of the cell membrane.     

Vidian nerve resection in chronic hypertrophic non allergic rhinitis: effects on histamine content, number and rate of degranulation processes of mast cells in nasal mucosa

The effects of Vidian nerve resection on the histamine content, number and rate of degranulation processes of mast cells in the respiratory tract of the nasal mucosa in patients with intractable chronic hypertrophic non-allergic rhinitis (CHNAR) have been investigated at various times after surgery. Preliminary data are also presented on the effects of Vidian nerve stimulation on the same parameters. The Vidian nerve was stimulated during surgery before resection. After neurotomy the histamine content was significantly lower than before but the values became less low with the passing of time. The number of mast cells per microscopic field and their degranulation index were significantly lower after surgery than before it. Stimulation determines a significant reduction in the number of mast cells per microscopic field and a parallel reduction in histamine content. These data establish a relationship between cholinergic activity and secretory response of mast cells and demonstrate a role of the parasympathetic nerve supply in the pathogenesis of CHNAR. The great reduction in the number of mast cells and histamine content also suggests that the parasympathetic nerve supply could play a role in the regulation of histamine synthesis and uptake.     

Muscarinic cholinergic receptor binding in rat mast cells

Specific [³H]-QNB binding was present in isolated, purified, intact rat mast cells and in crude membrane preparations. The binding is saturable, time- and temperature-dependent. Cholinergic agents inhibit selectively the binding: atropine is the most effective of the antagonists while oxotremorine is the most potent of the muscarinic agonists. It is concluded that rat mast cells are provided with muscarinic cholinergic receptors.