Effect of in vivo and in vitro ethanol on adrenergic and purinergic responses of the bisected rat vas deferens to low and high frequency pulses

Alcohol Use Disorders and Their Harmful Effects on the Contractility of Skeletal, Cardiac and Smooth Muscles

Alcohol misuse has deleterious effects on personal health, family, societal units, and global economies. Moreover, alcohol misuse usually leads to several diseases and conditions, including alcoholism, which is a chronic condition and a form of addiction. Alcohol misuse, whether as acute intoxication or alcoholism, adversely affects skeletal, cardiac and/or smooth muscle contraction. Ethanol (ethyl alcohol) is the main effector of alcohol-induced dysregulation of muscle contractility, regardless of alcoholic beverage type or the ethanol metabolite (with acetaldehyde being a notable exception). Ethanol, however, is a simple and "promiscuous" ligand that affects many targets to mediate a single biological effect. In this review, we firstly summarize the processes of excitation-contraction coupling and calcium homeostasis which are critical for the regulation of contractility in all muscle types. Secondly, we present the effects of acute and chronic alcohol exposure on the contractility of skeletal, cardiac, and vascular/ nonvascular smooth muscles. Distinctions are made between in vivo and in vitro experiments, intoxicating vs. sub-intoxicating ethanol levels, and human subjects vs. animal models. The differential effects of alcohol on biological sexes are also examined. Lastly, we show that alcohol-mediated disruption of muscle contractility, involves a wide variety of molecular players, including contractile proteins, their regulatory factors, membrane ion channels and pumps, and several signaling molecules. Clear identification of these molecular players constitutes a first step for a rationale design of pharmacotherapeutics to prevent, ameliorate and/or reverse the negative effects of alcohol on muscle contractility.

Phosphodiesterase 5 Inhibitors in Rapid Ejaculation

Rapid (premature) ejaculation (RE) is a very common sexual disorder. This condition may be primary or secondary to underlying disease. Control of RE has been primarily focused on behavioural therapy, topical anaesthetics, tricyclic antidepressants and selective serotonin reuptake inhibitors; however, an approved treatment does not exist. Recently, a number of clinical trials have studied the potential effectiveness of the phosphodiesterase (PDE)-5 inhibitor sildenafil in the treatment of RE. Results of most of these studies have been encouraging. Available data indicate that there is clinical, anatomical, physiological, pharmacological and genetic evidence to explain the efficacy of PDE5 inhibitors in RE. The rationale for the use of PDE5 inhibitors in the treatment of RE could be due to possible peripheral and central mechanisms. Possible peripheral ejaculation retarding capabilities may include modulation of the contractile response of the vas deferens (VD), seminal vesicles (SV), prostate and urethra, induction of a state of peripheral analgesia, and prolongation of the total duration of erection. Possible central mechanisms may involve lessening of the central sympathetic output. Furthermore, there is evidence from knockout mice to explain the efficacy of PDE5 inhibitors in RE. Mice lacking the gene for endothelial nitric oxide synthase develop a condition similar to RE. On the other hand, mice lacking the gene for heme oxygenase-2 develop a condition similar to delayed ejaculation. This review also discusses the findings against the use of these agents in RE. In conclusion, a review of the literature suggests the potential usefulness of PDE5 inhibitors as a promising line of therapy in RE but further studies are needed.