New therapies for treating hypertension: what every physician should know

Hypertension is a prevalent health problem and a major cause of morbidity and mortality in the United States. It is one of the most important modifiable risk factors for multiple medical problems including coronary artery disease, congestive heart failure, and end-stage renal disease. There are many efficacious antihypertension medications, each with its own indications and side effect profile. Furthermore, new drugs are being developed rapidly. This article features how to diagnose hypertension as well as describes pharmacological and nonpharmacological treatment options. The properties, proper use, and side effect profile of each of the nine classes of antihypertension drugs commonly used and three classes of medications on the horizon will be described. The purpose of this manuscript is to familiarize physicians with the antihypertension regimens commonly employed and to introduce drugs which may become available in the near future.

Vasorelaxant responses to endomorphins, nociceptin, albuterol, and adrenomedullin in isolated rat aorta

The endogenous peptides endomorphins 1 and 2 are newly discovered, potent, selective mu-opioid receptor agonists. In the present study, the effects of endomorphins 1 and 2 on vascular smooth muscle tone were investigated on isolated rings from rat aorta with and without endothelium. In rings precontracted with phenylephrine, endomorphins 1 and 2 at concentrations of 0.1 and 1.0 microM, nociceptin at concentrations of 1-100 microM, and adrenomedullin at concentrations of 0.01-1.0 microM induced concentration dependent relaxant responses. The endomorphins and nociceptin were less potent than adrenomedullin. No relaxation was induced by endomorphins 1 and 2 in aortic rings denuded of endothelium and precontracted with phenylephrine. The results of the present studies demonstrate that the endomorphins relax aortic vascular smooth muscle from the rat aorta by an endothelium-dependant mechanism.

Adrenomedullin Does Not Inhibit Human Platelet Aggregation

BACKGROUND: Adrenomedullin (ADM) is a hypotensive peptide isolated from human pheochromocytoma extracts discovered in 1993 using an assay system designed to monitor its ability to increase rat platelet adenosine 3',5'-cyclic monophosphate (cAMP) levels. Physiological mediators that elevate cAMP levels, such as prostaglandin (PG)E(1) and PGI(2), have also been shown to inhibit platelet aggregation. Therefore, we have chosen to investigate the effect of ADM, a peptide shown to increase platelet cAMP levels, on human platelet aggregation. METHODS AND RESULTS: Platelet-rich plasma prepared from blood donors was incubated with ADM (10(-9)-10(-6) M) for 1 min at 37 degrees C before the addition of a submaximal dose of adenosine 5'-diphosphate (ADP). ADM did not alter the platelet aggregatory response to ADP. PGE(1), a substance known to inhibit ADP-induced platelet aggregation (10(-6) M), however, inhibited ADP-induced platelet aggregation. In addition, the ADM induced a dose-dependent relation in rings of human chorionic arteries. CONCLUSIONS: These data may be interpreted to suggest that human platelets do not possess a functional ADM receptor couple with adenylate cyclase.

A novel alpha-type carbonic anhydrase associated with the thylakoid membrane in Chlamydomonas reinhardtii is required for growth at ambient CO2

A 29.5 kDa intracellular alpha-type carbonic anhydrase, designated Cah3, from the unicellular green alga Chlamydomonas reinhardtii is the first of this type discovered inside a photosynthetic eukaryote cell. We describe the cloning of a cDNA which encodes the protein. Immunoblot studies with specific antibodies raised against Cah3 demonstrate that the polypeptide is associated exclusively with the thylakoid membrane. The putative transit peptide suggests that Cah3 is directed to the thylakoid lumen, which is confirmed further by the presence of mature sized Cah3 after thermolysin treatment of intact thylakoids. Complementation of the high inorganic carbon concentration-requiring mutant, cia-3, with a subcloned cosmid containing the cah3 gene yielded transformants that grew on atmospheric levels of CO2 (0.035%) and contained an active 29.5 kDa alpha-type carbonic anhydrase. Although, cia-3 has reduced internal carbonic anhydrase activity, unexpectedly the level of Cah3 was similar to that of the wild-type, suggesting that the mutant accumulates an inactive Cah3 polypeptide. Genomic sequence analysis of the mutant revealed two amino acid changes in the transit peptide. Results from photosynthesis and chlorophyll a fluorescence parameter measurements show that the cia-3 mutant is photosynthetically impaired. Our results indicate that the carbonic anhydrase, extrinsically located within the chloroplast thylakoid lumen, is essential for growth of C.reinhardtii at ambient levels of CO2, and that at these CO2 concentrations the enzyme is required for optimal photosystem II photochemistry.