alpha1-adrenoceptor antagonists are first-line agents for the treatment of lower urinary tract symptoms suggestive of benign prostatic hyperplasia, while their adverse effects on sexual function are reported frequently in recent years, especially the induction of ejaculatory dysfunction. This review presents the distribution of alpha 1-adrenoceptors in the male genital system and the relationship of alpha1-adrenoceptors with ejaculatory function. It also highlights the interesting phenomenon of ejaculatory dysfunction related to these drugs and its possible mechanism, with the intention to provide some essential clues for further research on this problem as well as some references to safer use of these drugs in clinical settings.
Adrenergic alpha-1 Receptor Antagonists ; Adrenergic alpha-Antagonists ; adverse effects ; pharmacology ; Ejaculation ; physiology ; Erectile Dysfunction ; chemically induced ; physiopathology ; Humans ; Male ; Receptors, Adrenergic, alpha-1 ; physiology

We investigated the adrenergic sensitivity of afferent fibers in the L4 dorsal roots of rats with a unilateral ligation of the L5-L6 spinal nerves. About 12% of nociceptive fibers on the affected side were excited by sympathetic stimulation or by intra-arterial injection of norepinephrine which did not affect A beta-fiber activity. Sympathetic excitation of nociceptive fibers was suppressed by alpha 1-antagonist prazosin, while it was unaffected by alpha 2-antagonist yohimbine. Most of these fibers were excited by intra-arterial injection of alpha 1-agonist phenylephrine, without being affected by an injection of alpha 2-agonist clonidine. Sympathetic excitation was blocked by lidocaine applied near the receptive fields of recorded fibers. The results suggested that some nociceptors remaining intact after partial nerve injury become sensitive to sympathetic activity by the mediation of alpha 1-adrenoceptors in the peripheral endings.
Animal ; Male ; Nerve Fibers/physiology* ; Nociceptors/physiology* ; Norepinephrine/pharmacology ; Pain/physiopathology* ; Rats ; Rats, Sprague-Dawley ; Receptors, Adrenergic, alpha-1/physiology*

Kidney is one of the important organs of the body.With both excretory and endocrine functions,it plays a vital role in regulating the normal physiological state.As a precursor of the nitric oxide(NO)synthesis
Animals ; Arginine/physiology* ; Kidney/physiology* ; Muscle, Smooth, Vascular ; Nitric Oxide/physiology* ; Rats ; Receptors, Adrenergic, alpha-1/physiology* ; Renal Insufficiency/physiopathology* ; Signal Transduction ; Vasoconstriction

Alpha1a-adrenergic receptor (AR) primarily mediates the contraction of the prostatic and cavernous smooth muscles. Among clinically available alpha1-AR antagonists for the medical management of benign prostatic hyperplasia (BPH), tamsulosin has a modest selectivity for alpha1A- and alpha1D- over alpha1B-ARs. To compare the effects of various alpha1-AR antagonists on relaxation responses of cavernous and trigonal smooth muscles, isometric tension studies with relatively selective (tamsulosin) and non-selective (prazosin, doxazosin, and terazosin) alpha1A-AR antagonists, were conducted in the cavernous and trigonal muscle strips of rabbits (n=10 each). Tamsulosin had the strongest inhibitory effect on contraction of trigonal smooth muscle among the various alpha1-AR antagonists, and the inhibitory activities of prazosin, doxazosin, and terazosin were not statistically different. All alpha1-AR antagonists caused concentration-dependent relaxation of the cavernous muscle strips. Tamsulosin was shown to have greater potency than prazosin (more than 100-fold), doxazosin (more than 1000-fold), and terazosin (more than 1000-fold), in relaxation of cavernous smooth muscle. In conclusion, tamsulosin might be the most effective drug among the four commonly used alpha1-AR antagonists for the medical management of BPH. Tamsulosin might be a potential substitute for phentolamine in combination with vasoactive agents as an intracavernous injection therapy for patients with erectile dysfunction.
Adrenergic alpha-Antagonists/pharmacology* ; Animal ; Comparative Study ; Doxazosin/pharmacology* ; In Vitro ; Muscle Contraction/drug effects ; Muscle Relaxation/drug effects* ; Muscle, Smooth/physiology ; Muscle, Smooth/drug effects* ; Prazosin/pharmacology* ; Rabbits ; Receptors, Adrenergic, alpha-1/antagonists & inhibitors* ; Sulfonamides/pharmacology*

OBJECTIVETo observe the relaxant effect of Aike Mixture (AKM) on isolated bladder and prostatic urethral smooth muscle of rabbits.

METHODSThe isolated bladder and prostatic urethral smooth muscle from male rabbits were placed in a Magnus bath and smooth muscle contraction was measured using a biological signal acquisition and analysis system. The effects of AKM in combination with methoxyamine, carbachol and CaCl2 on the contractile tension of muscle strips were determined by cumulative dosing.

RESULTSAKM dose-dependently reduced contractile tension of bladder trigone smooth muscle (r=0.831, P<0.05), reduced contractile wave amplitude (r=0.837, P<0.05) and decreased contractile frequency (r=-0.917, P<0.01). AKM significantly inhibited the increases in smooth muscle contraction induced by methoxyamine, carbachol and CaCl2.

CONCLUSIONAKM dose-dependently inhibited the contraction of rabbit isolated bladder and prostatic urethral smooth muscle by antagonizing &alpha;1-adrenergic receptors and M-cholinergic receptors.

Animals ; Calcium Chloride ; pharmacology ; Carbachol ; pharmacology ; Drugs, Chinese Herbal ; pharmacology ; Hydroxylamines ; pharmacology ; In Vitro Techniques ; Male ; Muscle Contraction ; drug effects ; Muscle, Smooth ; drug effects ; physiology ; Neuromuscular Agents ; pharmacology ; Prostate ; drug effects ; physiology ; Rabbits ; Receptors, Adrenergic, alpha-1 ; metabolism ; Receptors, Muscarinic ; metabolism ; Urethra ; drug effects ; physiology ; Urinary Bladder ; drug effects ; physiology