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At least 19 recordsLinked to original sources
PubMed1978

Mechanism of blood pressure reduction by teprotide (SQ 20881) in rats.

The mechanism by which the angiotensin converting enzyme inhibitor, teprotide (SQ 20881), lowers blood pressure was assessed in anesthetized normotensive and spontaneously hypertensive (SHR) rats. Teprotide always was administered at a maximally effective dose of 1 mg/kg. In six normal Wistar rats, teprotide lowered blood pressure only after sodium depletion, an effect which was abolished by bilateral nephrectomy. Saralasin infusion (5 microgram/kg/min) into salt-depleted normal rats induced a blood pressure effect similar to that of teprotide. When administered in addition to saralasin infusion, teprotide did not reduce blood pressure further in normal rats or in SHR. When blood pressure of normal rats was raised by angiotensin II infusion (200 ng/kg/min), teprotide did not affect the induced blood pressure increase. In contrast, the pressure rise induced by angiotensin I infusion (230 ng/kg/min) was reversed by saralasin, but again concomitant administration of teprotide did not induce further blood pressure reduction. Thus, under the particular conditions of the present study, teprotide did not appear to exert its hypotensive effect by any mechanism other than inhibition of the renin-angiotensin system. Furthermore, given at a maximally effective dose to the rat, it produced no greater vasodepressor effect than did saralasin.

Angiotensin I↗
PubMedDate not supplied

Cardiovascular responses to isometric exercise and standing in normotensive subjects during converting enzyme inhibition with teprotide.

The hemodynamic responses to isometric exercise (hand grip) were investigated in normotensive subjects during a 150 mEq (n = 8) sodium diet and a 10 mEq (n = 6) sodium diet both before and after the administration of the converting enzyme inhibitor teprotide. Although teprotide significantly decreased the mean arterial pressure during both sodium intakes, the normal pattern of hemodynamic response to hand grip was preserved, that is mean arterial pressure was increased by hand grip mainly because of an increase in cardiac output. Changes of plasma catecholamines during hand grip were not affected by teprotide. In addition, the hemodynamic responses to standing were not substantially altered by teprotide. When fainting occurred (in the seated position) following the administration of teprotide, it was associated not only with a decrease in arterial pressure but also with a concurrent reduction in cardiac output. We conclude that angiotensin inhibition by teprotide does not significantly impair sympathetically mediated cardiovascular responses.

Adult↗
PubMed1981

Hormonal and blood pressure changes during converting enzyme inhibition by teprotide.

Changes induced by i.v. and subcutaneous teprotide in plasma renin, angiotensin I, angiotensin II, aldosterone and bradykinin were studied in a renal transplant patient with severe high renin hypertension, before and after trinephrectomy. The immediate reduction in BP produced by teprotide was not solely attributable to the inhibition of conversion of angiotensin I to angiotensin II, because there was also a transient increase in serum bradykinin; however, the prolonged antihypertensive effect of teprotide appeared independent of bradykinin. After trinephrectomy, teprotide lowered systolic BP but had no significant effect on diastolic BP or plasma bradykinin. beta-Blockade prevented the secondary increase in plasma renin which followed teprotide, thereby potentiating its anti-hypertensive effect.

Aldosterone↗
PubMed1987

Hypotensive effects of the renin inhibitor (RI-78) and the converting enzyme inhibitor (teprotide) in conscious monkeys.

Effects of the pentapeptide renin inhibitor (RI-78; Phe(4Cl)-Phe-Val-Tyr-Lys-NH2) and the angiotensin converting enzyme (ACE) inhibitor (teprotide) on mean arterial pressure (MAP) were examined in conscious monkeys (M. fascicularis). In salt depleted normotensive monkeys with a MAP of 95 +/- 4 mmHg and plasma renin activity (PRA) of 15.9 +/- 2.7 ngAI/ml/h, a bolus injection of a dose of 375 micrograms/kg of RI-78 caused a prompt hypotensive effect. Maximal hypotensive action was seen within 1 min, and MAP returned to the basal level within 15 min. With this dose, MAP was reduced by 20 +/- 6 mmHg. Teprotide (1 mg/kg) decreased MAP and reached a nadir after 13 min. There was no significant difference between maximal hypotensive responses seen with RI-78 (375 micrograms/kg) and with teprotide (1 mg/kg). Hypotensive effects of RI-78 and teprotide were also examined in acute renal hypertensive monkeys with a MAP of 125 +/- 5 mmHg and a PRA of 27.1 +/- 5.7 ngAI/ml/h. Again, similar hypotensive effects were observed. We conclude that antihypertensive effect of RI-78 is comparable to that seen with teprotide.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1980

Hemodynamic effects of the converting enzyme inhibitor teprotide in normal- and high-renin hypertension.

The hemodynamic effects of the converting enzyme inhibitor teprotide (SQ 20881) were investigated in five patients with normal plasma renin activity who were normotensive during the study (group I), in five patients with hypertension and normal plasma renin activity (group II), and in five patients with hypertension and high plasma renin activity (group III). No significant hemodynamic changes were observed during teprotide administration in group I. In group II there was a decrease in mean arterial pressure by 10 +/- 2% (p < 0.005) that was associated with a decrease by 16 +/- 7% (p < 0.05) in stroke volume and cardiac output, possibly due to venodilatation and without a concurrent change in total peripheral resistance. In group III the larger decrease of 19 +/- 4% (p < 0.005) in mean arterial pressure was due to a decrease by 30 +/- 3% (p < 0.005) in peripheral resistance. In this group stroke volume and cardiac output increased by 13 +/- 2% (p < 0.025). There were no compensatory changes in heart rate despite the decrease in mean arterial pressure and vasodilatation. These results indicate that teprotide decreases arterial pressure by a dual hemodynamic mechanism. Cardiac output is increased by teprotide in patients with high-renin hypertension who exhibit the greatest decrements in peripheral resistance.

Adult↗
PubMed1981

Failure of chronic administration of the angiotensin I-converting enzyme inhibitor, Teprotide (SQ 20881), to affect the ultrastructure of the adrenal cortex and the aldosterone secretion in the rat.

Administration of Teprotide (SQ 20881), an angiotensin I-converting enzyme inhibitor for up to 10 weeks at a dose of 3 mg. per kg., subcutaneously, twice a day in the rat, effected no change in the ultrastructure of the adrenal cortex nor in the concentration of serum aldosterone. A significant increase (p less than 0.05) in renin granulation indices which was already apparent after 3 weeks of treatment with Teprotide was even more definitive after 10 weeks (p less than 0.01). Moderate renal hypertrophy was present in rats receiving the drug for 3 weeks. Findings pertaining to aldosterone production differed from those reported following acute administration of Teprotide wherein a decrease in the production of serum aldosterone and an increase in plasma renin activity was observed. It has been suggested that decreased aldosterone production following acute administration of Teprotide is a consequence of decreased stimulus of the zona glomerulosa due to diminished synthesis of angiotensin II. If this is the case, mechanisms other than angiotensin II stimulation of the zona glomerulosa must control aldosterone synthesis, perhaps through hormones of the adrenal cortex. Another possibility could be that angiotensin II synthesis may be obtained, after an interval, through an alternative pathway.

Adrenal Cortex↗
PubMed1985

Captopril and teprotide as discriminators of angiotensin-converting enzyme activity in brain tissue.

Titrations of angiotensin-converting enzyme (ACE; E.C. 3.4.15.1) present in human serum, as well as in homogenates prepared from post-mortem human caudate or mouse (C57BL1/6J) whole brain tissue, were performed with the selective ACE inhibitors, captopril (SQ 14225) and teprotide (SQ 20881). ACE activity present in human serum was more sensitive to inhibition by either inhibitor than the activity present in the brain homogenates. The inhibition curves for the titration of the human serum activity by both inhibitors were sigmoidal while the inhibition curves for the ACE activity present in the brain homogenates were more complex. These results suggest that the brain homogenates contained: at least two species of enzyme activity with properties similar to ACE but with differing affinities for the inhibitors, or substances without ACE activity that are capable of competing with ACE for the binding of the inhibitors. Therefore, measurements of captopril or teprotide-sensitive peptidase activity as well as inhibitor-binding activity may not always reflect ACE concentrations in brain tissue.

Animals↗
PubMed1985

[Human erythrocyte prolyl endopeptidase II hydrolysing teprotid, an inhibitor of peptidyl peptidase from snake venom].

The paper is concerned with the action of 1200-fold purified prolylendopeptidase II (PE-E) from human erythrocytes and the action of highly purified prolyl-D-L-alanine peptidyl hydrolase (PE-A) from bovine adenohypophysis on teprotide (BPP9a, SQ 20881), a nonapeptide from venom of the snake Bothrops Jararaca--an inhibitor of peptidyl dipeptidase A (carboxycathepsin). Both the purified preparation PE-E and highly purified preparation PE-A split teprotide at the bonds Pro3-Arg4 and Pro5-Gln6. The Pro8-Pro9-OH bond was not split by the two enzymes. The comparative characteristics of the properties of PE-E and PE-A are presented and the possible physiological role of these enzymes is discussed.

Animals↗
PubMed1982

Coronary hemodynamic effects of angiotensin inhibition by captopril and teprotide in patients with congestive heart failure.

The coronary hemodynamic effects of vasodilator therapy with angiotensin-converting enzyme inhibitors (captopril and teprotide) were studied in 11 patients with ischemic heart disease and severe congestive heart failure (CHF). Over 2 hours, systemic vascular resistance was reduced from 2,408 +/- 240 to 1,715 +/- 170 dynes . s . cm-5 (p less than 0.001), and cardiac output improved 18%, resulting in lower arterial pressure (101 +/- 8 to 86 +/- 5 mm Hg, p less than 0.001) and left ventricular filling pressure (30 +/- 2 to 21 +/- 2 mm Hg, p less than 0.001). Coronary sinus thermodilution blood flow paralleled perfusion pressure but did not significantly vary overall (160 +/- 20 to 133 +/- 12 ml/min, difference not significant [NS]). Coronary vascular resistance was unchanged. Although the left ventricular stroke work index rose slightly (37.7 +/- 8.8 to 41.3 +/- 7.9 g l m/m2, p less than 0.05), there was no change in the coronary arteriovenous oxygen content difference (10.8 +/- 1.0 to 10.4 +/- 1.0 ml/10 ml, NS) or calculated myocardial oxygen consumption (16.4 +/- 1.9 to 13.9 /- 1.6 ml/min, NS). The heart rate-systolic blood pressure product declined significantly during this period (8,824 +/- 703 to 7,087 +/- 514 beats . mm Hg, p less than 0.02); this relief of cardiac effort was a function of the pretreatment plasma renin activity. A derived index of external myocardial efficiency improved 37% (19 +/- 3 to 26 +/- 6, p less than 0.05), reflecting greater left ventricular work without increased oxygen demand. Enhancement of myocardial performance after converting enzyme inhibition appears dependent on reduction of angiotensin-mediated ventricular afterload and preload. The lack of coronary vasomotor effects in patients with advanced ischemic cardiomyopathy may reflect limited coronary vascular reserve. Improvement of heart failure in these patients developed without evidence of myocardial ischemia, since balance was maintained between oxygen supply and demand.

Aged↗
PubMed1987

Effects of teprotide, captopril and enalaprilat on arterial wall kininase and angiotensin converting activity.

We have previously shown that the hypotensive action of angiotensin I (ANG I) converting enzyme (ACE) inhibitors is temporally related to a long-lasting inhibition of kininase activity in the arterial wall. More recently, we showed that conversion of ANG I in the perfused mesenteric vascular bed was not inhibited by enalaprilat at concentrations above those which maximally inhibited kininase activity. The present study extends these observations to two other ACE inhibitors and to another vascular bed, the rat hindlimb preparation. Like enalaprilat, captopril (0.06-1.5 mumol/l) or teprotide (0.4-10 mumol/l) did not inhibit the conversion of ANG I in the perfused mesenteric bed, although the response to bradykinin was substantially potentiated, indicating that the ACE inhibitor decreased kininase activity. In the perfused hindlimb preparations, enalaprilat reduced kininase activity without altering the conversion of ANG I. Enalaprilat or captopril administered to rats caused a decrease in mean arterial blood pressure that lasted for over 24 h. In mesenteric preparations taken from animals 24 h after treatment with ACE inhibitors, kininase activity was inhibited whereas converting activity was unchanged. Therefore, the long-lasting hypotensive effect of ACE inhibition is apparently related to a prolonged inhibition of kininase activity in the arterial wall, which is believed to be the target for ACE inhibitor activity.

Angiotensin I↗
PubMed1984

Reduction in hypertension-induced protein synthesis in the rat pulmonary trunk after treatment with teprotide (SQ 20881).

Angiotensin II has been previously implicated as a mediator of vasoconstriction during the development of hypoxic pulmonary hypertension. The effect of angiotensin-converting enzyme inhibition with teprotide (SQ 20881) on development of pulmonary hypertension was determined by measurement of the drug's ability to modify hypertension-induced protein synthetic changes in the rat pulmonary trunk. Rats were injected with either SQ 20881 (2 mg/kg body wt every 8 hr) or saline vehicle during exposure to chronic hypoxia at 0.5 atm for either 3 or 7 days. Comparisons were made of tissue weight, absolute protein content, and in vitro synthesis of collagen and noncollagen protein of the pulmonary trunks of SQ-treated hypoxic, SQ-treated normoxic, saline-treated hypoxic, and saline-treated normoxic rats. Treatment of hypoxic rats with SQ 20881 was found to significantly decrease right ventricular pressure, tissue weight, absolute protein content, and in vitro protein synthesis after 7 days compared to saline-treated hypoxic rats. Neither right ventricular hypertrophy nor the development of polycythemia was decreased by SQ 20881 treatment.

Angiotensin-Converting Enzyme Inhibitors↗
PubMed1985

[Synthesis and effect of affinity-labeled analogs and partial sequences of the bradykinin potentiating nonapeptide BPP9 alpha (teprotide)].

Affinity labeled analogues and partial sequences of the bradykinin potentiating nonapeptide BPP9 alpha inhibit the BPP9 alpha induced potentiation of the bradykinin action on the isolated guinea pig ileum. The labeled nonapeptides are more active than the labeled partial sequences. The inhibition of the potentiating action of BPP9 alpha demonstrates, that the influence on bradykinin action is not only a result of the inhibition of peptidyl dipeptide hydrolase.

Affinity Labels↗
PubMed1984

Reversal by angiotensins II and III of the effects of converting enzyme inhibition on renal electrolyte excretion in rats.

Experiments were carried out in anaesthetized rats to compare the abilities of angiotensin II (A II) and angiotensin III (A III) to reverse the effects of angiotensin converting enzyme inhibition (Teprotide) on salt and water excretion. In rats infused with Teprotide, significant increases in urine flow and sodium excretion were observed and arterial blood pressure decreased. Addition of A II (10 pmol min-1) to the Teprotide infusion reduced renal excretion of sodium and water to control values and excretion of potassium to below control. Blood pressure increased to a value significantly higher than that during the control period. In a separate group of rats the natriuretic and diuretic effects of Teprotide were reversed by a similar dose of A III (10 pmol min-1). A primarily angiotensin-mediated action is indicated for the renal effects of Teprotide. Although angiotensins II and III appeared to be equipotent in their abilities to reverse the renal responses to Teprotide, A II caused an increase in arterial blood pressure that was not seen with A III. In a third group of rats A II (10 pmol min-1) was added to the Teprotide infusion and an aortic snare located between the renal arteries was tightened to prevent any increase in left renal perfusion pressure. During this period the rate of sodium excretion from the left kidney was significantly lower than from the right kidney. It is concluded that in the absence of any accompanying 'pressure natriuresis' A II is more potent than A III in its ability to reverse the natriuretic action of Teprotide. The elevation of blood pressure to above control values by a dose of A II only just sufficient to reverse the Teprotide-induced natriuresis suggests that the concentration of angiotensin in the kidney is higher than in plasma and supports the concept of an intrarenal renin-angiotensin system. In the rat both A II and A III may affect renal salt and water excretion by a combination of mechanisms involving glomerular, vascular and tubular receptors. The possibility is raised that differential effects of the active angiotensins on these mechanisms may participate in the regulation of sodium excretion.

Angiotensin II↗
PubMedDate not supplied

Inotropic cardiac and vascular actions of [Ala7]angiotensin analogs.

Angiotensins I, II, and III are potent cardiac inotropic agents, but vasoconstrictor and steroidogenic activities compromise their use in conditions of cardiac dysfunction. This study examines the inotropic and vascular actions of [alanyl7]-substituted angiotensin analogs in field-stimulated rabbit left atria and isometrically contracting aortic strips. Angiotensin II increased cardiac contractility in a dose-dependent manner with an ED50 of 30 nM. Sarcosine substitution at the amino terminus of angiotensin II increased its potency 10-fold. Inhibition of converting enzyme with teprotide (10 microgram/ml) had no effect on contractile responses to angiotensin II or [Sar1]angiotensin II. [Ala7]Angiotensin II was a weaker cardiac stimulant than angiotensin II, but addition of teprotide enhanced its potency to that of angiotensin II. [Sar1, Ala7]Angiotensin II also was equipotent to [Sar1]angiotensin II in the presence of teprotide. The potency of angiotensin I as an inotropic agent (ED50 = 100 nM) was significantly less than that of angiotensin II, and the angiotensin I response was attenuated by teprotide. [Sar1, Ala7]Angiotensin I was a more effective inotropic agent following teprotide administration. These findings indicate that atrial converting enzyme metabolizes angiotensin I and the [Ala7] analogs of angiotensin I and II. Angiotensin II and [Sar1]angiotensin II had activities in aorta similar to those in atria. As previously reported for uterus, [Ala7]Angiotensin II was inactive in aorta whether teprotide was present or not. The decapeptides were equally potent in the aorta and atria. Sarcosine substitution at the NH2 terminus also was observed to attenuate cardiac selectivity. These data indicate that [Ala7]angiotensin analogs are cardioselective inotropic agents.

Alanine↗
PubMed1987

Effect of inhibition of central angiotensin pressor mechanisms on blood pressure in spontaneously hypertensive rats.

The present experiments were designed to elucidate the role of central angiotensin II (AII) mechanisms in maintenance of established hypertension in adult spontaneously hypertensive rats (SHR) by determining the blood pressure response to chronic intraventricular (i.v.t.) infusion of the converting enzyme inhibitor teprotide or the AII receptor antagonist 1sar,8Thr-AII (sarthran). Male SHR (240-300 g) were given chronic indwelling arterial and venous catheters and bilateral lateral cerebral ventricular cannulae. The acute pressor responses to successive intravenous infusions of AII (sarthran experiments) or angiotensin I (AI; teprotide experiments) and to an intraventricular bolus injection of AII or AI were determined in the conscious rats. A 5-day intraventricular infusion of sarthran (1 or 6 micrograms/h) or teprotide (10 micrograms/h) in isotonic saline was maintained by subcutaneously implanted osmotic minipumps, and pressor responses were retested on the 5th day of intraventricular infusion. Five-day intraventricular sarthran infusion at 1 and 6 micrograms/h reduced the pressor response to intraventricular AII by 48 and 74%, respectively, while intraventricular teprotide (10 micrograms/h) inhibited the pressor response to intraventricular AI by 25%. None of the intraventricular infusions significantly decreased pressor responsiveness to intravenous AII or AI. In separate groups of SHR, tail-cuff blood pressure was monitored before, during, and after a 1-week intraventricular teprotide infusion (10 micrograms/h) or successive intraventricular infusions of sarthran at 1 microgram/h for 2 weeks followed by 6 micrograms/h for 1 week. Neither chronic intraventricular sarthran or teprotide caused a significant lowering of blood pressure in SHR.(ABSTRACT TRUNCATED AT 250 WORDS)

Angiotensin II↗