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R A Ferrone

Publications and source records attributed to R A Ferrone.

14 recordsLinked to original sources
PubMed1994

The stereospecific effects of isoflurane isomers in vivo.

The anesthetic potency of racemic isoflurane and the optically pure stereoisomers was examined in rats. The (+) isomer was 53% more potent than the (-) isomer (minimum alveolar concentration (MAC) = 1.06 +/- 0.07% vs. 1.62 +/- 0.02%, P < 0.05). MAC for racemic isoflurane was 1.32 +/- 0.03%. Both stereoisomers and the racemic isoflurane produced similar depression of arterial pressure. However, the (+) isomer blunted the cardiovascular response to a painful stimulus to a greater extent than did an equi-MAC dose of the (-) isomer. These are the first data to describe pharmacological differences between stereoisomers of a volatile anesthetic administered in vivo by the conventional route (inhaled) and measuring the clinically relevant index of anesthesia, MAC. These data are consistent with a receptor-mediated anesthetic mechanism by volatile anesthetics.

Anesthesia Recovery Period↗
PubMed1984

Hypertension after ending captopril administration: pathogenesis in 2-kidney, 1-clip rat.

We have previously shown that continuous captopril administration prevents hypertension from developing in the two-kidney, one-clip (2K, 1C) rat. The present investigation was designed to determine the mechanism(s) producing the hypertension. In one series of experiments captopril prevented pressure from increasing during an 8-wk treatment period. Relative to the last day of treatment, mean arterial pressure and total peripheral resistance (TPR) were increased and cardiac output was unchanged at 3, 7, and 28 days after captopril cessation. Plasma renin activity (PRA) was unchanged 3, 7, and 14 days after captopril cessation but was elevated at 28, 49, and 56 days after captopril cessation only in 2K, 1C rats with severe hypertension (systolic blood pressure greater than 180 mmHg). Guanethidine (45 mg/kg po, bid) did not prevent the development of 2K, 1C hypertension but did prevent the hypertension from developing after cessation of captopril. Blockade of the prostaglandin system with indomethacin (5 mg/kg + 50 micrograms X kg-1 X min-1) and of the kallikrein-kinin system with aprotinin (25,000 KIU + 150 KIU X kg-1 X min-1) for 2 h had no effect on captopril's antihypertensive effect. Additionally, no change in sodium or water balance was observed after captopril cessation. Taken together these data demonstrate that hypertension after captopril cessation is due to an increase in TPR. Additionally, the rise in TPR is due to both the sympathetic nervous and the renin-angiotensin systems since both systems must be functional before pressure rises.

Animals↗
PubMed1983

Relative contribution of vasopressin and angiotensin II to the altered renal microcirculatory dynamics in two-kidney Goldblatt hypertension.

The renal microcirculation was assessed in non-clipped kidneys of 23 Munich-Wistar rats with two-kidney one-clip Goldblatt hypertension. Four weeks after placement of a renal arterial clip, mean systemic arterial pressure averaged 163 +/- 5 mm Hg in hypertensive rats as compared to 108 +/- 2 in sham-operated controls (n = 6 rats). Non-clipped kidneys in hypertensive rats were characterized by higher glomerular capillary hydraulic pressures, single nephron glomerular filtration rate, and afferent arteriolar resistance. The glomerular capillary ultrafiltration coefficient was significantly reduced in hypertensive rats. In 10 of these rats, intravenous infusion of the angiotensin antagonist, saralasin, or the converting enzyme inhibitor, SQ20881, led to significant reductions in systemic arterial pressure and in afferent and efferent arteriolar resistance, on average by 8 +/- 3%, 15 +/- 4%, 28 +/- 5%, respectively. These changes were associated with significant increase in glomerular plasma flow, while ultrafiltration coefficient remained unaffected. In the presence of saralasin or SQ20881, infusion of a specific antagonist of the vascular action of arginine vasopressin led to significant systemic but not renal vasodilation. Thus, whereas systemic arterial pressure fell further, on average by 23 +/- 2%, renal arteriolar resistance remained constant, resulting in marked reduction in glomerular capillary hydraulic pressures (by 18 +/- 2%) and glomerular plasma flow rate (by 28 +/- 10%). Because of these pronounced reductions in glomerular pressures and flows induced by vasopressin antagonist, single nephron glomerular filtration rate fell markedly in hypertensive rats (by 34 +/- 6%) despite normalization of ultrafiltration coefficient. When hypertensive rats (n = 7) were treated with vasopressin antagonist alone, a modest fall in systemic arterial pressure was again observed in the absence of changes in renal arteriolar resistance. Due to this selective extrarenal vasodilatory action of vasopressin antagonist, glomerular capillary hydraulic pressure, plasma flow rate, and single nephron glomerular filtration rate again fell markedly. When these vasopressin antagonist pre-treated hypertensive rats were given saralasin or SQ20881, marked reductions in renal arteriolar resistance were observed in association with a significant increase in glomerular plasma flow rate. These observations made during acute inhibition of angiotensin II and vasopressin indicate that both of these vasopressin hormones may play important roles in maintaining systemic hypertension in hypertensive rat. By virtue of its preferential constrictor effects on extrarenal rather than renal vasculature vasopressin serves to maintain high glomerular pressures and flows in the non-clipped kidney of Goldblatt hypertensive rats.

Angiotensin II↗
PubMed1982

Angiotensin II is a necessary component for the development of hypertension in the two kidney, one clip rat.

The current study was undertaken to define the role of the renin-angiotensin system in the development of hypertension in the two kidney, one clip Goldblatt rat. Captopril was administered orally (100 mg/kg/day) to two groups of rats (n = 8 each) 24 hours before and each day after unilateral renal artery clipping (0.2 mm internal diameter): the drug was given for either 16 weeks (group I) or 24 weeks (group II). Sham-operated (n = 5) and Goldblatt (n = 8) rats not receiving captopril were prepared for comparisons of plasma renin activity and systolic blood pressure. Indomethacin (20 mg/kg/day subcutaneously) was administered for 48 hours concomitantly with captopril to the rats in group I. In group II, systolic blood pressure was monitored for 7 weeks after cessation of captopril. Continual captopril administration to Goldblatt rats completely prevented the rise in systolic blood pressure, a rise that was observed in Goldblatt rats not receiving captopril. Whereas systolic blood pressure of captopril-treated rats approximated 100 mm Hg throughout the study, that of Goldblatt rats not receiving the drug increased to nearly 180 mm Hg within 6 weeks after clipping. Systolic blood pressure of sham-operated rats remained normal. Indomethacin did not change systolic blood pressure in the drug-treated rats in group I. On cessation of captopril therapy in group II, systolic blood pressure increased gradually in a manner that paralleled the development of the disease in the Goldblatt rats that did not receive captopril. Plasma renin activity was determined in Goldblatt and sham-operated rats at either 16 weeks (group I) or 24 weeks (group II) after clipping; the rats from either group with mild hypertension (systolic blood pressure less than 180 mm Hg) had normal plasma renin activity whereas those with severe hypertension (systolic blood pressure greater than 180 mm Hg) had greatly elevated plasma renin activity. In summary, captopril can completely prevent the increase in systolic blood pressure for up to 24 weeks in Goldblatt rats, and this hypotensive effect is not mediated by the prostaglandins. It is concluded that the renin-angiotensin system is a necessary component of the hypertensive process in this experimental model.

Angiotensin II↗
PubMed1980

Hemodynamic and metabolic responses to repeated blood sampling in the rat.

Repeated blood sampling (0.2 ml) in the conscious rat during the course of 10 cardiac index measurements using the Fick procedure did not alter the cardiac index as measured initially (285 ml x min-1 x kg-1). However, oxygen consumption and hematocrit were reduced 7-19% and 4-14%, respectively. Replacement of blood removed during sampling with donor blood prevented these responses, but also led to reduced cardiac index and arterial oxygen content, 22-28% and 10-21%, respectively. In additional studies in anesthetized rats, hemorrhage (25 ml/kg) increased plasma K+ by 29% and reduced plasma Na+ by 3%, suggesting that compensatory fluid replacement originated in cells as well as interstitium. This fluid replacement after blood loss helps sustain normal systemic hemodynamics, but blood loss can produce metabolic alterations that should be taken into account in any biochemical study. Although metabolic alterations can be prevented by replacing lost blood with donor blood, cardiopulmonary function may be adversely affected.

Animals↗
PubMed1980

Comparison of the acute and chronic hemodynamic effects of captopril and guanethidine in spontaneously hypertensive rats.

The present study compared the hemodynamic effects of captopril with those of guanethidine as well as with a combination of these two drugs in conscious male spontaneously hypertensive rats. Acutely, captopril or guanethidine or a combination of the two lowered arterial pressure to similar levels. The reduction in pressure with captopril alone or in combination with guanethidine, was due to a lowering of all organ vascular resistances. Guanethidine alone lowered pressure by reducing cardiac output. Chronically, captopril or guanethidine lowered arterial pressure to similar levels by reducing organ vascular resistances to comparable levels, particularly skeletal muscle, skin and splanchnic organs. Combination of these two drugs had an additive effect on the reduction of arterial pressure and organ vascular resistances. Since, chronically, the addition of guanethidine to captopril therapy enhanced rather than attenuated the hemodynamic changes induced by captopril, these drugs are probably acting by different mechanisms and the mechanisms of action of captopril does not require an intact sympathetic nervous system.

Animals↗
PubMed1979

Prevention of the development of spontaneous hypertension in rats by captopril (SQ 14,225).

Indirect systolic blood pressure (SBP) was monitored in male, weanling, spontaneously hypertensive rats (SHR) maintained on water for 16 weeks (group A) or on captopril therapy (100 mg/kg/day in drinking water) for 4 (group B), 8 (group C), 12 (group D), 16 (group E) weeks. Weanling SHR of group A developed typical, time-related hypertension over a 16-week observation period. In marked contrast, SHR receiving captopril did not develop hypertension. Discontinuation of captopril after 4, 8, 12 or 16 weeks resulted in the usual development of hypertension. There was a transient increase in water consumption of drug treated rats which returned to normal by 8 weeks of dosing. Conversely, when captopril therapy was discontinued after 4, 8 or 12 weeks, there was a transient decrease in water intake, the magnitude of which was inversely related to the duration of drug therapy. These results demonstrate that daily captopril therapy was able to completely prevent the development of spontaneous hypertension. Explanations for the mechanism(s) underlying the influence of captopril on blood pressure and water intake remain speculative.

Animals↗
PubMed1979

Ether-induced vasodilation in the rat.

The hypotensive effect of ether in rats was investigated by the direct Fick technique to determine whether hypotension was produced by reduced cardiac output or decreased total peripheral resistance. Relative to the conscious state, ether anesthesia decreased mean arterial pressure 9%, total peripheral resistance 47%, oxygen extraction 37%, and heart rate 7%; changes were qualitatively similar to those produced by hydralazine (0.5 mg/kg, i.v.) except that hydralazine did not decrease heart rate. These effects were no longer present two hours after withdrawal of ether. This study demonstrated that ether anesthesia in rats has a potent systemic arterial vasodilating action which is offset by increased cardiac output, resulting in mild hypotension.

Anesthesia↗
PubMed1978

Regional blood flows measured in conscious rats by combined Fick and microsphere methods.

Regional blood flow measurements made by the radioactive microsphere technique were studied in conscious rats. A femoral arterial reference sample blood flow was measured directly, and at the same time indirectly by the combined use of direct Fick cardiac output and microsphere techniques. A significant correlation (r = .81, P less than .01) was obtained between direct and indirect blood flow values when 200--400 microspheres were trapped in the reference sample. When 100--200 microspheres were trapped, regional blood flow was 32% below true flow (P less than .01); and cardiac output, calculated by the reference sample method, was 57% greater than Fick cardiac output (P less than .01). When three consecutive Fick determinations and microsphere injections (20,000 per injection, 15 micrometer diam) were made in conscious rats, significant correlations were obtained among the first, second, and third regional blood flow measurements (r = .95, P less than .01). The results have demonstrated that cardiac output and reference blood flow can be measured with accuracy and precision in the conscious rat by the radioactive microsphere procedure.

Animals↗
PubMedDate not supplied

Sympathoadrenal and renin-angiotensin systems in the development of two-kidney, one clip renal hypertension in rats.

The relative roles of the sympathetic nervous system and renin-angiotensin system in the development of two-kidney renal hypertension were studied using four groups of rats: Group I = vehicle control; Group II = 6-OH-dopamine (2 weeks prior to renal clipping then weekly throughout the study); Group III = adrenal medullectomy plus vehicle; Group IV = 6-OH-dopamine plus adrenal medullectomy. Six weeks after clipping of a single renal artery, plasma renin activity (PRA) was comparably elevated in all groups. However, mean blood pressure (MBP) of Group II was lower than that of Group I controls (154.7 +/- 6.8 vs 197.3 +/- 6.6 mm Hg respectively). The MBP of Group III (207.0 +/- 5.2 mm Hg) was not different from that of Group I whereas in Group IV (134.2 +/- 18.0 mm Hg) it was markedly lower. All groups of rats were given a single dose of captopril (30 mg/kg p.o.) to inhibit the renin-angiotensin system. Despite differences in starting MBP, captopril caused similar reductions (38-50%) of MBP and increases in PRA in all groups. Similar results were obtained in two-kidney renal hypertensive rats with hypertension of 12 weeks' duration. It is concluded that the sympathetic nervous system does not contribute to the elevated PRA in two-kidney renal hypertensive rats but does contribute significantly to the development of hypertension in this model.

Adrenal Glands↗