Plasma Noradrenaline Concentration and α-Adrenoceptor-Mediated Vasoconstriction in Normotensive and Hypertensive Man

Kiowski, Wolfgang; Bühler, Fritz R.; Vanbrummelen, P; Amann, Franz W.

doi:10.1042/cs0600483

Cited by 42 publications

(10 citation statements)

References 17 publications

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“…Our findings are supported by recent studies in vivo with intact normal volunteers (Elliot et al, 1981) and with forearm circulation in young and old subjects (Kiowski et al, 1981).…”

Section: The Effect Of Age On the Responses Of Human Isolated Arteriesupporting

confidence: 82%

The effect of age on the responses of human isolated arteries to noradrenaline.

Scott¹,

Reid²

1982

Brit J Clinical Pharma

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“…Our findings are supported by recent studies in vivo with intact normal volunteers (Elliot et al, 1981) and with forearm circulation in young and old subjects (Kiowski et al, 1981).…”

Section: The Effect Of Age On the Responses Of Human Isolated Arteriesupporting

confidence: 82%

The effect of age on the responses of human isolated arteries to noradrenaline.

Scott¹,

Reid²

1982

Brit J Clinical Pharma

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“…Plasma NA is derived from the peripheral sympathetic nervous system (von Euler et al, 1954;Glowinski et al, 1965;Cryer, 1976) and reflects the activity of the system (Lake et al, 1976;Kopin et al, 1978;Saar & Gordon, 1979;Watson et al, 1979;Kiowski et al, 1981), although some care may be necessary in interpretation of the results due to different patterns of organ release and extraction (Brown et al, 1981). Secretion of renin is partly under the control of the sympathetic nervous system (Gordon et al, 1967;Winer et al, 1969) so that PRA is also a marker of sympathetic activity (Kotchen et al, 1971), but other factors such as local renal haemodynamics (Pettinger et al, 1973;Mathias et al, 1975) and sodium intake (Watson et al, 1980) may also influence PRA.…”

Section: Discussionmentioning

confidence: 99%

Differential blockade of alpha‐adrenoceptors by indoramin.

Nicholls¹,

O'Connor²,

Harron³

et al. 1984

Brit J Clinical Pharma

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1 The effect of equihypotensive single oral doses of indoramin (mean dose 67 mg), phenoxybenzamine (mean dose 50 mg), hydralazine (mean dose 133 mg) and placebo on arterial pressure and heart rate in the supine and standing position was studied in six normal volunteers. Observations were made before and at 2 and 4 h after drug administration.2 Plasma noradrenaline (NA) was measured at each time interval in the supine position, and after 4 min of standing. Plasma renin activity (PRA) was measured at each time interval after 30 min in the standing position. 3 The three active drugs reduced systolic arterial pressure in the standing position to a similar extent (indoramin, -24 mm Hg; phenoxybenzamine, -23.4 mm Hg; hydralazine, -30.4 mm Hg). The maximum effect of indoramin and phenoxybenzamine was observed at 4 h, and of hydralazine at 2 h after drug administration. 4 The reductions of arterial pressure in the standing position were accompanied by increases in heart rate, plasma NA and PRA. Small increases were observed after indoramin (heart rate, + 9.2 beats min-'; plasma NA, + 126 pg/ml; PRA, + 0.33 ng angiotensin 1 ml-' h-1), greater increases after phenoxybenzamine (heart rate, + 20; plasma NA, + 210; PRA, + 0.47), and the greatest increases after hydralazine (heart rate, + 26; plasma NA, + 250; PRA, + 1.16). 5 In the supine position, indoramin and phenoxybenzamine produced no effect on arterial pressure, heart rate or plasma NA. Hydralazine produced small reductions in diastolic pressure, which were accompanied by an increase in heart rate of 25.5 beats min (P < 0.01 when compared to placebo) and in plasma NA of 223 pg ml-'(P < 0.05). 6 Plasma NA, PRA and heart rate increased together and may be regarded as three interdependent indices of sympathetic activity. 7 Indoramin reduced the degree of increase of plasma NA, PRA and heart rate per unit fall in pressure, when compared to phenoxybenzamine and hydralazine. The effect of phenoxybenzamine and hydralazine on the degree of increase was similar. 8 The results are consistent with the hypothesis that indoramin produces selective postsynaptic al-adrenoceptor blockade in man, and therefore produces relatively less tachycardia and NA increase than does a non-selective a-adrenoceptor antagonist (phenoxybenzamine) or an arteriolar vasodilator (hydralazine).Keywords indoramin phenoxybenzamine hydralazine a-adrenoceptors 719 720 D. P. Nicholls et al.

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“…This dose of IA PHEN decreases forearm vasoconstriction during norepinephrine infusion from 67 to 15% without affecting systemic blood pressure or heart rate (30). The dose of IA PROP blocks isoproterenol induced vasodilation without systemic effects (C.A.S., unpublished data).…”

mentioning

confidence: 99%

Systemic and Local Adrenergic Regulation of Muscle Glucose Utilization During Hypoglycemia in Healthy Subjects

et al. 2002

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Adrenergic responses are crucial for hypoglycemic recovery. Epinephrine increases glucose production, lipolysis, and peripheral insulin resistance as well as blood flow and glucose delivery. Sympathetic activation causes vasoconstriction and reduces glucose delivery. To determine the effects of ␣-and ␤-adrenergic activity on muscle glucose uptake during hypoglycemia, we studied forearm blood flow (FBF) (plethysmography), arteriovenous glucose difference (AV-diff), and forearm glucose uptake (FGU) during insulin infusion with 60 min of euglycemia followed by 60 min of hypoglycemia. Twelve healthy subjects (27 ؎ 5 years of age) were randomized to intravenous propranolol (IV PROP, 80 g/min), intravenous phentolamine (IV PHEN, 500 g/min), intra-arterial propranolol (IA PROP, 25 g/min), intra-arterial phentolamine (IA PHEN, 12 g/min per 100 ml forearm tissue), and saline (SAL). FBF increased during hypoglycemia with SAL (P < 0.001) but not with IA or IV PROP. FGU (P ‫؍‬ 0.015) and AV-diff (P ‫؍‬ 0.099) fell during hypoglycemia with IA PROP but not with IV PROP. FBF increased during hypoglycemia with IA and IV PHEN (P < 0.005). AV-diff fell during hypoglycemia with IA and IV PHEN (P < 0.01), but FGU was unchanged. Blood pressure fell (P < 0.001), and adrenergic and neuroglycopenic symptoms increased with IV PHEN (P < 0.01). Thus, systemic but not local propranolol prevents a decrease in forearm glucose extraction during hypoglycemia, suggesting that epinephrine increases peripheral muscular insulin resistance through systemic effects. ␣-Adrenergic activation inhibits vasodilation and helps maintain brain glucose delivery. Diabetes 51:734 -742, 2002 H ypoglycemia is the limiting factor in achieving good glycemic control in patients with type 1 diabetes. Discovering the physiologic mechanisms by which the body normally protects itself from hypoglycemia and how these mechanisms are altered in diabetes will increase our understanding of the pathophysiology and treatment of diabetes. We have demonstrated that during insulin-induced hypoglycemia, forearm blood flow (FBF) increases (1). The increase in flow augments glucose delivery and maintains normal glucose uptake despite a fall in glucose extraction. Local ␤-adrenergic blockade inhibits the vasodilation and leads to decreased forearm glucose uptake (FGU) during hypoglycemia, whereas local ␣-adrenergic blockade increases flow and increases FGU. In contrast to this, other authors have demonstrated that systemic combined ␣-and ␤-blockade and ␤-blockade alone lead to increased peripheral glucose uptake during hypoglycemia (2-6). The metabolic mechanisms by which increases in ␣-and/or ␤-adrenergic activity decrease peripheral glucose uptake during hypoglycemia are not clearly defined.Peripheral glucose uptake is dependent on two factors, fractional cellular glucose uptake and the amount of glucose delivered to the tissues (7,8). It is unclear whether the sympathetic activation that accompanies hypoglycemia is associated with decreased glucose transport or decreased glucose d...

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Plasma Noradrenaline Concentration and α-Adrenoceptor-Mediated Vasoconstriction in Normotensive and Hypertensive Man

Cited by 42 publications

References 17 publications

The effect of age on the responses of human isolated arteries to noradrenaline.

The effect of age on the responses of human isolated arteries to noradrenaline.

Differential blockade of alpha‐adrenoceptors by indoramin.

Systemic and Local Adrenergic Regulation of Muscle Glucose Utilization During Hypoglycemia in Healthy Subjects

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