Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

---

Query: UMLS:C0020538 (hypertension)
170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

The incidence of erectile dysfunction (ED), defined as the persistent inability to achieve or maintain an erection sufficient for satisfactory sexual performance, increases with age and with risk factors for vascular disease, including smoking, diabetes and hypertension. Penile erection results from an arousal-induced synthesis of nitric oxide (NO) in nonadrenergic-noncholinergic nerves (NANC), endothelial cells and cavernosal smooth muscle cells (SMCs). Vasodilation and relaxation of cavernosal SMCs engorges the corpora cavernosa with blood at arterial pressure. The subcellular mechanism by which tumescence occurs involves NO-induced activation of soluble guanylate cyclase, increased cyclic guanosine monophosphate (cGMP) levels and activation of cGMP-dependent protein kinase (PKG). PKG phosphorylates numerous ion channels and pumps, each promoting a reduction in cytosolic calcium. In particular, PKG activates high-conductance Ca2+(-)sensitive K+ (BKCa) channels, which hyperpolarize the arterial and cavernosal SMC membranes, causing relaxation. This mechanism appears to be compromised with age and with vascular disease, leading to ED. Thus, increasing cavernosal nitric oxide synthase (NOS) expression, cGMP levels and/or BKCa channel expression is an effective therapy for experimental ED. Future therapies may involve augmenting K+ channel expression by gene transfer or increasing channel function through the use of Type 5 phosphodiesterase (Type 5 PDE) inhibitors or phosphatase inhibitors.
...
PMID:Potassium channels and erectile dysfunction. 1237 24

Sildenafil is the first oral therapeutic agent for erectile dysfunction. Sildenafil is a selective inhibitor of cGMP-specific phosphodiesterase (PDE-5). Penile erection involves relaxation of the corpus cavernosum, an event mediated by NO and cGMP. The biological actions of cGMP are terminated by phosphodiesterase enzymes and PDE-5 is the major cGMP metabolising enzyme in this tissue. Sildenafil is relatively safe compared to erection injectables because it does not relax on isolated human corpus cavernosum, and does not cause priapism. Due to the tendency of abuse of sildenafil, its adverse cardiovascular associations with myocardial infaraction, ventricular arrhythmia and hypertension need to be alerted.
...
PMID:[Mode of action of sildenafil]. 1256

Diagnostic procedures for erectile dysfunction (ED) are still mandatory because ED can be the presenting symptom for a variety of diseases such as diabetes mellitus, coronary artery disease, atherosclerosis, hypertension and hyperlipidemia. Invasive testing for ED has decreased due to the high responder rate for oral PDE-5 inhibitors.
...
PMID:[Diagnosis of erectile dysfunction--what is still needed today?]. 1456 79

Erectile dysfunction (ED) often is caused by endothelial dysfunction and may be a sign that a patient has vascular disease elsewhere in the body. Risk factors for coronary artery disease such as lipid abnormalities, smoking, diabetes, and hypertension also are risk factors for ED. Oral therapy for ED, such as sildenafil, inhibits phosphodiesterase-5 (PDE-5) and the breakdown of cyclic guanosine monophosphate. PDE-5 inhibitors have been shown to be safe and effective for the therapy for ED, but remain contraindicated in patients receiving organic nitrates. These agents are mild vasodilators and are being investigated for their treatment potential for patients with pulmonary hypertension, heart failure, and endothelial dysfunction.
...
PMID:Erectile dysfunction in the cardiac patient. 1462

Primary pulmonary arterial hypertension (PPH) is a rare disease of undetermined origin and fatal prognosis. A better prognosis is associated with at least 20% reduction of either pulmonary artery pressure or pulmonary vascular resistance ("responders") in acute vasodilatory trials. Prostacycline (PGI2) or nitric oxide (NO) administration promises valuable results. NO is one of the most powerful vasodilating agents, endogenously produced by endothelial cells. It migrates from these cells to smooth muscle cells and stimulates production of cGMP, that induces smooth muscle relaxation. cGMP is hydrolyzed by 5-phopshodiesterase (PDE-5). Several papers documenting hypotensive effect in pulmonary circulation of specific PDE5 inhibitor--sildenafil (Viagra--Pfizer) have been published recently. We present a case report of a 26 year old female patient with PPH--"nonresponder" in a trial with NO--and NO responder after sildenafil administration. Initial values were: mean pulmonary artery pressure (mPAP) was 58 mmHg, pulmonary vascular resistance was 10.9 Wood's units. mPAP and PVR during NO inhalation (40 ppm) decrease from 62 to 54 mmHg and from 11.4 to 10.3 Wood's units, respectively. Measurements performed 60 minutes after 50 mg of sildenafil orally disclosed a 19% reduction of mPAP and 21% reduction of PVR. NO inhalation caused further decrease of both parameters: mPAP was decreased for additional 28% and PVR for additional 36% in comparison to initial results. Neither peripheral hypotension nor other side effects were observed. A month-long administration of sildenafil in a dose 2 x 25 mg daily reduced mPAP and PVR to values reported for the acute trial. Physical capability improved also. It was assessed as increased distance in a six-minute-walk test (280 vs. 400 m in the first week of treatment, and 330 m in a fourth week of treatment). Echocardiography showed moderate decrease of right ventricle and right atrium diameters, along with decrease of the degree of relative tricuspid regurgitation with unchanged maximal velocity of regurgitant wave. Specific PDE-5 inhibitors might be an attractive alternative in the treatment of pulmonary hypertension in case the above noted observations are confirmed.
...
PMID:[Sildenafil reduces pressure and pulmonary resistance and increases susceptibility of pulmonary arteries to nitric oxide in primary pulmonary arterial hypertension]. 1609 62

Three different phosphodiesterase 5 (PDE5) inhibitors are currently available for the treatment of erectile dysfunction: sildenafil, vardenafil and tadalafil. The differences between these 3 are limited: tadalafil has a long duration of action, while vardenafil has a rapid onset of action after intake. Various studies have suggested that there is an improvement in the partners' sex lives when men use a PDE5 inhibitor for erectile dysfunction. The introduction of PDE5 inhibitors has renewed the interest in PDE inhibitors in general, for example in the treatment of pulmonary hypertension. In the near future PDE inhibitors may be used for various disorders as chronic obstructive pulmonary disease, benign prostatic hyperplasia, hypertension and coronary heart disease.
...
PMID:[Phosphodiesterase inhibitors: effectiveness and new applications]. 1690 Oct 64

Phosphodiesterase 5 inhibitors, such as sildenafil, vardenafil and tadalafil, are now approved for the treatment of erectile dysfunction. They inhibit the cGMP-specific isoform 5 of phosphodiesterase, resulting in cGMP accumulation, which, for example in smooth muscle cells, reduces muscular tone. In the cardiovascular system, they slightly reduce arterial systemic blood pressure. This moderate effect was also shown in combination with many antihypertensive drugs. But the important contraindication is the concomitant use of PDE 5 inhibitors with any drug serving as a nitric oxide donor, as this combination can lead to significant arterial hypotension. Caution is needed in patients on alpha-blocking agents. In general, this class of drugs was not shown to exhibit direct deleterious effects on the myocardium or promote arrhythmias. Furthermore, statistical evaluations did not demonstrate an increased risk for patients taking PDE 5 inhibitors in comparison with an adequate control population. Many patients suffering from erectile dysfunction may be characterized by multiple cardiovascular risk factors or even ischemic heart disease, suggesting an increased baseline risk. While in many forms of erectile dysfunction, these agents seem to be very effective, it becomes clear that endothelial dysfunction is an attractive target of PDE 5 inhibitors and may also be the underlying cause in many types of erectile dysfunction. In addition, these agents seem to be very effective in lowering pulmonary arterial pressure, which might provide the opportunity to treat primary and some forms of secondary pulmonary hypertension, perhaps in combination with inhaled nitric oxide or other pulmonary arterial vasodilators. Sildenafil was approved for treatment of primary arterial hypertension in the U.S. in June 2005. Recently, direct cardioprotective effects were described in animal research, resembling preconditioning-like effects, which may, under certain conditions, also be applicable in clinical research.
...
PMID:Cardiovascular effects of phosphodiesterase 5 inhibitors. 1701 41

Single injection of a small quantity of phenol into the cortex of one kidney in rats results in development of persistent hypertension (HTN) which is thought to be mediated by activation of renal afferent and efferent sympathetic pathways and sodium retention. Nitric oxide (NO) plays a major role in regulation of renal vascular resistance, tubular Na(+) reabsorption, pressure natriuresis, and thereby systemic arterial pressure. The present study was performed to test the hypothesis that chronic renal injury-induced HTN may be associated with dysregulation of NO system in the kidney. Accordingly, urinary NO metabolite (NO(x)) and cGMP excretions as well as renal cortical tissue (right kidney) expressions of NO synthase (NOS) isoforms [endothelial, neuronal, and inducible NOS, respectively (eNOS, nNOS, and iNOS)], NOS-regulatory factors (Caveolin-1, phospho-AKt, and calmodulin), and second-messenger system (soluble guanylate cyclase [sGC] and phosphodiesterase-5 [PDE-5]) were determined in male Sprague-Dawley rats 4 wk after injection of phenol (50 mul of 10% phenol) or saline into the lower pole of left kidney. The phenol-injected group exhibited a significant elevation of arterial pressure, marked reductions of urinary NO(x) and cGMP excretions, downregulations of renal tissue nNOS, eNOS, Phospho-eNOS, iNOS, and alpha chain of sGC. However, renal tissue AKt, phospho-AKT, Calmodulin, and PDE-5 proteins were unchanged in the phenol-injected animals. In conclusion, renal injury in this model results in significant downregulations of NOS isoforms and sGC and consequent reductions of NO production and cGMP generation by the kidney, events that may contribute to maintenance of HTN in this model.
...
PMID:Effect of renal injury-induced neurogenic hypertension on NO synthase, caveolin-1, AKt, calmodulin and soluble guanylate cyclase expressions in the kidney. 1712 86

Erectile dysfunction is a common, multifactorial disorder that is associated with aging and a range of organic and psychogenic conditions, including hypertension, hypercholesterolemia, diabetes mellitus, cardiovascular disease, and depression. Penile erection is a complex process involving psychogenic and hormonal input, and a neurovascular nonadrenergic, noncholinergic mechanism. Nitric oxide (NO) is believed to be the main vasoactive nonadrenergic, noncholinergic neurotransmitter and chemical mediator of penile erection. Released by nerve and endothelial cells in the corpora cavernosa of the penis, NO activates soluble guanylyl cyclase, which increases 3',5'-cyclic guanosine monophosphate (cGMP) levels. Acting as a second messenger molecule, cGMP regulates the activity of calcium channels as well as intracellular contractile proteins that affect the relaxation of corpus cavernosum smooth muscle. Impaired NO bioactivity is a major pathogenic mechanism of erectile dysfunction. Treatment of erectile dysfunction often requires combinations of psychogenic and medical therapies, many of which have been only moderately successful in the past. The advent of oral phosphodiesterase type 5 (PDE-5) inhibitors, however, has greatly enhanced erectile dysfunction treatment; patients have demonstrated high tolerability and success rates for improved erectile function. The efficacy of the PDE-5 inhibitors also serves to illustrate the importance of the NO-cGMP pathway in erectile function since these agents counteract the degradation of NO-generated cGMP. Because not all patients respond to PDE-5 inhibitors, additional therapies are being investigated, such as soluble guanylyl cyclase activators and NO donors, which act on NO-independent and NO-dependent pathways, respectively.
...
PMID:The role of nitric oxide in erectile dysfunction: implications for medical therapy. 1717 Jun 6

Pulmonary vascular remodeling due to overgrowth of pulmonary artery smooth muscle cells (PASMC) is a major cause for the elevated vascular resistance in patients with idiopathic pulmonary arterial hypertension (IPAH). Increased cytosolic Ca(2+) concentration, resulting from enhanced capacitative Ca(2+) entry (CCE) and upregulated transient receptor potential (TRP) channel expression, is involved in stimulating PASMC proliferation. The current study was designed to determine the impact of cAMP, a second messenger that we hypothesized would blunt aspects of PASMC activity, as a possible contributor to IPAH pathophysiology. Short-term (30 min) pretreatment with forskolin (FSK; 10 muM), a direct activator of adenylyl cyclase, in combination with the cyclic nucleotide phosphodiesterase inhibitor isobutylmethylxanthine (IBMX; 200 muM), attenuated CCE in PASMC from normal subjects, patients without pulmonary hypertension (NPH), and patients with IPAH. The FSK-mediated CCE inhibition was independent of protein kinase A (PKA), because the PKA inhibitor H89 negligibly affected the decrease in CCE produced by cAMP. By contrast, longer (4 h) treatment with FSK (with IBMX) attenuated CCE in normal and NPH PASMC but enhanced CCE in IPAH PASMC. This enhancement of CCE was abolished by PKA inhibition and associated with an upregulation of TRPC3. In addition, cAMP increased TRPC1 mRNA expression in IPAH (but not in normal or NPH) PASMC, an effect blunted by H89. Furthermore, iloprost, a prostacyclin analog that increases cAMP, downregulated TRPC3 expression in IPAH PASMC and FSK-mediated cAMP increase inhibited IPAH PASMC proliferation. Although a rapid rise in cellular cAMP decreases CCE by a PKA-independent mechanism, sustained cAMP increase inhibits CCE in normal and NPH PASMC but increases CCE via a PKA-dependent pathway in IPAH PASMC. The divergent effect of cAMP on CCE parallels effects on TRPC expression. The results suggest that the combined use of a PKA inhibitor and cAMP-elevating drugs may provide a novel approach for treatment of IPAH.
...
PMID:Pulmonary artery smooth muscle cells from normal subjects and IPAH patients show divergent cAMP-mediated effects on TRPC expression and capacitative Ca2+ entry. 1718 22


<< Previous 1 2 3 4 5 6 7 8 Next >>

---