Optimal Vascular Protection: A Case for Combination Antihypertensive Therapy

A novel antihypertension agent, sargachromenol D from marine brown algae, Sargassum siliquastrum, exerts dual action as an L-type Ca2+ channel blocker and endothelin A/B2 receptor antagonist

We isolated the novel vasoactive marine natural products, (5E,10E)-14-hydroxy-2,6,10-trimethylpentadeca-5,10-dien-4-one (4) and sargachromenol D (5), from Sargassum siliquastrum collected from the coast of the East Sea in South Korea by using activity-guided HPLC purification. The compounds effectively dilated depolarization (50mMK+)-induced basilar artery contraction with EC50 values of 3.52±0.42 and 1.62±0.63μM, respectively, but only sargachromenol D (5) showed a vasodilatory effect on endothelin-1 (ET-1)-induced basilar artery contraction (EC50=9.8±0.6μM). These results indicated that sargachromenol D (5) could act as a dual antagonist of l-type Ca2+ channel and endothelin A/B2 receptors. Moreover, sargachromenol D (5) lowered blood pressure in spontaneous hypertensive rats (SHRs) 2h after oral treatment at a dose of 80mg/kg dose and the effect was maintained for 24h. Based on our ex vivo and in vivo experiments, we propose that sargachromenol D (5) is a strong candidate for the treatment of hypertension that is not controlled by conventional drugs, in particular, severe-, type II diabetes-, salt-sensitive, and metabolic disease-induced hypertension.

Epidemiology of male sexual dysfunction

Male sexual dysfunction includes erectile dysfunction (ED), ejaculation disorders, orgasmic dysfunctions, and disorders of sexual interest/desire. Although current epidemiologic research supports the high prevalence of ED worldwide, incidence data are limited. Furthermore, prevalence data on other male sexual dysfunctions are also limited whereas incidence data are lacking. These epidemiologic data vary widely due to the different definitions used, the method of sampling, and the unknown value of the instruments used to assess sexual dysfunction. Many of the epidemiologic studies are old and associated with poor methodology. Although risk factors for ED are well described, there are almost no data for risk factors in other sexual dysfunctions. The impact of modification of risk factors in sexual dysfunctions is extremely interesting. To provide evidence-based data, there is an urgent need for new, properly designed epidemiological research.

Phosphodiesterase type 5 inhibitors: the day after

OBJECTIVE

Review the literature on phosphodiesterase type 5 inhibitors (PDE5-Is), addressing critical issues in their current and future use, assessing unanswered questions, and identifying research needs.

METHODS

A MEDLINE search was conducted on PDE5-Is, with emphasis on clinical trials and experience, for interpretation and analysis of their present and future role.

RESULTS

Although approximately 40 million patients with erectile dysfunction have been treated successfully worldwide with the three available PDE5-Is, inappropriate instructions, lack of follow-up, and lack of patient-centered care models are the main reasons for "non-response," leading to drop-out rates of >50%. Patients with severe neurologic damage, diabetes mellitus, or severe vascular disease may be resistant to PDE5-Is. Preservation of corporal smooth muscle with chronic administration of PDE5-Is has been reported and substantial evidence indicates that these drugs have beneficial effects on endothelium and cardiovascular function; sildenafil has been approved for the treatment of idiopathic pulmonary hypertension. Improvement of lower urinary tract symptoms in men with benign prostatic hyperplasia after PDE5-I administration has been also suggested.

CONCLUSIONS

The data indicate the necessity for (1) exploration of the pharmacologic characteristics of the three PDE5-Is; (2) research on their pharmacologic differences because some actions seems to be drug-specific; (3) development of alternative management strategies, such as chronic, low, everyday doses of PDE5-Is, if the monthly cost is affordable; and (4) clinical trials on use of PDE5-Is to treat other chronic conditions. The door for innovative therapeutic approaches will open, specifically for cross-risk factor treatment with PDE5-Is or their use in combination treatments or new multimodal pills that take advantage of drugs that exert pleiotropic vascular actions.