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  • 1
    Electronic Resource
    Electronic Resource
    Hypotensive effects of diltiazem to normals and essential hypertensives (1983)
    Springer
    European journal of clinical pharmacology 25 (1983), S. 475-480 
    Details
    ISSN: 1432-1041
    Keywords: hypotensive effect ; diltiazem ; plasma level ; normotension ; essential hypertension ; plasma renin ; arterial vasodilatation
    Source: Springer Online Journal Archives 1860-2000
    Topics: Chemistry and Pharmacology , Medicine
    Notes: Summary The hypotensive effect of acute and long-term, intravenous and oral administration of the calcium antagonist, diltiazem, was investigated in 8 normotensive volunteers and 55 patients with essential hypertension. Diltiazem i.v. infusion of 45 mg/h (0.5 mg/min, then 1.0 mg/min, each for 30 min rapidly decreased both blood pressure (BP) from 164±22/98±8 to 144±15/86±9 mmHg (mean±SD) and total peripheral resistance from 32.6±8.4 to 25.3±5.4 mmHg/l/min (p〈0.001), and increased stroke volume from 58.2±9.5 to 64.2±8.6 ml/beat (p〈0.05). It altered neither heart rate nor cardiac output in the hypertensives (n=10). Oral diltiazem 60 mg rapidly decreased BP from 155±10/103±6 to 142±12/90±8 mmHg after 3 hours (p〈0.01/p〈0.001) in hypertensives (n=8), but not in normotensives (n=8). Diltiazem 90 mg p.o. decreased BP from 157±15/102±9 to 129±13/83±8 mmHg (p〈0.01) in hypertensives (n=15), and reduced the heart rate from 71±8 to 65±8 beats/min (p〈0.01). The drug did not change plasma renin activity either in normotensives or hypertensives. The fall in diastolic BP was correlated with the plasma diltiazem concentration (r=0.910, n=6, p〈0.05). Long-term treatment with diltiazem 30mg t.d.s. decreased BP from 163±12/104±8 to 145±9/88±9 mmHg (p〈0.001, n=13), and 60mg t.d.s. decreased BP from 169±15/102±6 to 148±13/87±8 mmHg (p〈0.001, n=8), and significantly reduced the heart rate (p〈0.01) in hypertensives. Thus, the hypotensive action of diltiazem, which is due to arterial dilatation, is effective, either on intravenous or oral administration, during acute and long-term treatment of essential hypertension.
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00542114
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  • 2
    Electronic Resource
    Electronic Resource
    Electrophysiological analysis of bicarbonate permeation across the peritubular cell membrane of rat kidney proximal tubule (1984)
    Springer
    Pflügers Archiv 401 (1984), S. 34-42 
    Details
    ISSN: 1432-2013
    Keywords: Basolateral HCO 3 − transport ; pH ; $$p_{{\text{CO}}_{\text{2}} } $$ ; Carbonic anhydrase ; Anion substitution
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract The membrane potential response of proximal tubular cells to changing HCO 3 − concentrations was measured in micro-puncture experiments on rat kidney in vivo. No significant effect was noticed when luminal bicarbonate concentration was changed. Changing peritubular HCO 3 − by substitution with Cl− resulted in conspicuous membrane potential transients, which reached peak values after 100–200 ms and decayed towards near control with time constants of ∼2s. The polarity of the potential changes and the dependence of the initial potential deflections on the logarithm of HCO 3 − concentration suggest a high conductance of the peritubular cell membrane for HCO 3 − buffer, but not for Cl−, SO 4 2− , or isethionate. At constant pH $$t_{{\text{HCO}}_{\text{3}}^ - } $$ was estimated to amount to ∼0.68. At constant $$p_{{\text{CO}}_{\text{2}} } $$ , $$t_{{\text{HCO}}_{\text{3}}^ - } $$ was even greater because of an additional effect of OH− or respectively H+ gradients across the cell membrane. The secondary repolarization may be explained by passive net movements of K+ and HCO 3 − across the peritubular cell membrane, which result in a readjustment of intracellular HCO 3 − to the altered peritubular HCO 3 − concentration. Application of carbonic anhydrase inhibitors in the tubular lumen reduced the initial potential response by one half and doubled the repolarization time constant. The same effect occurred instantaneously when the inhibitor was applied—together with the HCO 3 − concentration step—in the peritubular perfusate. This observation demonstrates that membrane bound carbonic anhydrase is somehow involved in passive rheogenic bicarbonate transfer across the peritubular cell membrane, and suggests that HCO 3 − permeation might occur in form of CO2 and OH− (or H+ in opposite direction).
    Type of Medium: Electronic Resource
    URL: http://dx.doi.org/10.1007/BF00581530
    Library Location Call Number Volume/Issue/Year Availability
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    Paper (German National Licenses)
    Fulltext
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