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Biomedical subjects

W Dachman

Publications and source records attributed to W Dachman.

6 recordsLinked to original sources
PubMed2000

Alterations of venous drug reactivity in humans: acquired and genetic factors.

Until recently, studies dealing with veins have almost always been the neglected part of vascular research. Recent data show an increasing rate of venous disease, and increasing evidence supports a role for veins in systemic diseases. The authors discuss and comment on findings of recent studies on venous drug reactivity. Alterations in venous reactivity to alpha- and beta-adrenergic, NO-dependent, and other drugs have been shown in many genetically determined and acquired conditions, such as hypertension, smoking, and aging. In some of them, the changes of venous responsiveness are most likely secondary to another process, while in others the they seem to play a primary role in the development of systemic disease states. Studying the drug reactivity of the venous system more extensively provides useful information for clinicians and researchers and will no doubt help to further knowledge of the normal and pathologic processes of the vasculature.

Animals↗
PubMed1998

Decreased beta2 adrenergic mediated venodilatation in Native Americans.

BACKGROUND: A considerable body of research has been accumulated regarding the pathogenesis and treatment of hypertension in Whites (Caucasians) and in Blacks. This research has led to more effective therapies geared specifically towards these ethnic groups. Unfortunately, very little information is available regarding the pathogenesis of hypertension and the effect of antihypertensive treatment in Native Americans (North-American Indians). Ethnic variability in the response to adrenergic mediated stimulation has been previously described, and reduced compliance of the venous system has been suggested among the possible mechanisms responsible for essential hypertension. The aim of this study was to compare venous responsiveness between Native Americans and Whites to vasoactive substances. METHODS: The alpha1-adrenergic agonist, phenylephrine and the beta2-adrenergic agonist isoproterenol were studied in 10 Native American and White volunteers. The dorsal hand vein technique was used, which is a simple, relatively non-invasive method to study the response to vasoactive substances, in vivo. RESULTS: The maximal venodilatory response to isoproterenol in the Native American group was 53.2+/-27.5%; while in the White group it was 103.4+/-66.0% (p<0.05). The maximal venoconstriction for phenylephrine in the Native American subject group was similar to that of the White group (85.4+/-24.0% vs. 89.4+/-10.9%) (p = n.s.). CONCLUSIONS: Based on our findings, we can anticipate that Native Americans may respond differently to antihypertensive therapy. However, further investigation needs to be done with an eye towards the development of drug therapy and treatment strategies tailored to this specific population.

Adrenergic alpha-Agonists↗
PubMed1996

Evidence for genetic variability in venous responsiveness.

Alterations in adrenergic mediated vascular responsiveness and glucose metabolism have been implicated in the pathogenesis of essential hypertension. We sought for a human model to study possible interactions between the two pathogenetical factors. In a group of Latin-Americans there is a predominance of diabetes mellitus, impaired glucose tolerance and obesity, while the rate of hypertension is unexpectedly low (lower than in the normal population). Here we demonstrate attenuated alpha 1 adrenergic mediated vasoconstriction in the above group, suggesting a possible protective mechanism against the development hypertension.

Adrenergic alpha-Agonists↗
PubMed1996

Effect of ACE inhibition by benazepril, enalapril and captopril on chronic and post exercise proteinuria.

Although post exercise proteinuria has long been known, its exact pathophysiology is unclear. Our objective was to determine whether long-term angiotensin converting enzyme (ACE) inhibition by different ACE inhibitors had an influence on post exercise proteinuria. We studied 14 patients who also had mild, chronic proteinuria caused by diabetes mellitus or chronic glomerulonephritis. We compared changes both in chronic (baseline) and post exercise proteinuria, during and after treatment with three different ACE inhibitors, with appropriate washout periods for the three drugs to all 14 patients. Proteinuria (mg/24 hours +/- SD), prior to the treatment was 682 +/- 92. Proteinuria after treatment for 30 days with benazepril was 464.4 +/- 82.6 (p < 0.001), with enalapril: 477.1 +/- 105.5 (p < 0.001), and captopril: 504.7 +/- 100.1 (p < 0.001). Proteinuria three days after discontinuing the treatment with benazepril was 532.4 +/- 113.5, (p < 0.01), with enalapril: 561.3 +/- 128.5, (p < 0.01), and with captopril: 620.8 +/- 101.8, p = n.s. Post exercise proteinuria prior to treatment (mg/min. +/- SD) was: 1.38 +/- 0.32, vs. after a 30-day treatment period with benazepril: 0.81 +/- 0.19 (p < 0.001), enalapril: 0.95 +/- 0.24, (p < 0.001), captopril: 1.09 +/- 0.27 (p < 0.02). Post exercise proteinuria three days after discontinuing the treatment was (blood pressure already back to baseline): in case of benazepril: 1.26 +/- 0.36 (p = n.s.), of enalapril: 1.17 +/- 0.46 (p = n.s.), and of captopril: 1.34 +/- 0.41 (p = n.s.). We conclude that the renin-angiotensin system plays a significant role in the pathogenesis of post exercise proteinuria; the antiproteinuric effect of ACE inhibition in exercise-induced proteinuria seems to be associated chiefly with the hemodynamic changes due to these drugs, whereas in chronic proteinuria the antiproteinuric and antihypertensive effects are, at least partially, dissociated.

Adult↗
PubMed1992

Pharmacological tolerance to alpha 1-adrenergic receptor antagonism mediated by terazosin in humans.

Chronic administration of alpha 1-receptor antagonists is associated with loss of clinical efficacy, especially in congestive heart failure, although the mechanism is uncertain. To evaluate changes in venous alpha 1-adrenoceptor responsiveness during chronic alpha 1-adrenoceptor blockade, dose-response curves to phenylephrine and angiotensin II were constructed in 10 healthy subjects before, during, and after administration of terazosin 1 mg orally for 28 d. Terazosin initially shifted the dose-response curve of phenylephrine to the right, with a significant increase in ED50 for phenylephrine from a control value of 102 to 759 ng/min on day 1 of terazosin (P < 0.001). However, by day 28, the dose-response curve had shifted back towards baseline with an ED50 of 112 ng/min. After discontinuing terazosin, the ED50 for phenylephrine remained near the baseline value, indicating no evidence of supersensitivity to phenylephrine. There was no change in responsiveness to angiotensin II during the course of treatment with terazosin. Plasma terazosin concentrations were stable throughout the period of drug administration. The mean Kd of terazosin was estimated as 11 +/- 15 nM in the first few days of treatment. This study demonstrates that pharmacological tolerance to the alpha 1-adrenoceptor blocking action of terazosin occurs in man and may be responsible for loss in efficacy with chronic therapy.

Adrenergic alpha-Antagonists↗