Disease relevance of B-HT 920

• Acidosis had no effect on baseline diameter of the three vessel types, indicating a lack of effect on "intrinsic tone." Acidosis also had no effect on large microvessel sensitivity to phenylephrine but markedly reduced responses to B-HT 933 [1].
• Treatment with the PLC inhibitor U-73122 but not pertussis toxin blocked B-HT 933-induced rises in inositol-1,4,5-trisphosphate and intracellular calcium concentration [2].
• Peripheral prejunctional alpha 2-adrenoceptor blockade was measured as the reversal of B-HT 933-induced inhibition of an electrically evoked tachycardia in the pithed rat [3].
• E. coli endotoxin (0.01, 0.1 and 1 microgram/kg i.v.) 1 h before alpha 2-adrenoceptor agonists B-HT 933 and clonidine (i.v.) antagonized their bradycardiac and hypotensive effects in intact rats [4].
• To confirm the presence of alpha 2-mediated vasoconstriction in human vasculature, the effect of selective alpha 1- and alpha 2-agonists (methoxamine and B-HT 933) and antagonists (indoramin and Yohimbine) was studied in fourteen patients with mild, uncomplicated, essential hypertension [5].

Psychiatry related information on B-HT 920

• B-HT 933 decreased the motor activity by a yohimbine-sensitive mechanism [6].

High impact information on B-HT 920

• After plasma volume expansion, B-HT 933 showed no primary effect on LpA but heightened the response of arterial blood pressure, glomerular transcapillary pressure gradient, and LpA to AII [7].
• In euvolemic rats, B-HT 933 caused SNGFR to decline as the result of a decrease in glomerular ultrafiltration coefficient (LpA), an effect that was blocked by saralasin [7].
• Apparent pD2(-log ED50) values for large arterioles and venules were, respectively, as follows: norepinephrine (7.41 and 7.15), phenylephrine (5.95 and 5.41), and B-HT 933 (5.05 and 5.06) [8].
• We studied postsynaptic alpha-adrenoceptors in human blood vessels by measuring the influence on forearm blood flow induced by intra-arterial infusions of selective alpha 1- and alpha 2-adrenoceptor agonists (methoxamine, B-HT 933, clonidine and guanfacine) and antagonists (doxazosin and yohimbine) [9].
• In one set of studies, the systemic infusion of the alpha 2-agonist B-HT 933 rendered nephron GFR, nephron plasma flow, and proximal reabsorption sensitive to reduction by L-NMMA after renal denervation [10].

Chemical compound and disease context of B-HT 920

• 2 Antagonist activity at alpha 2-adrenoceptors was determined against the inhibitory effects of clonidine on tachycardia induced by electrical stimulation of cardiac sympathetic nerves and against the pressor responses to B-HT-933 injection [11].

Biological context of B-HT 920

• To identify the signal pathways coupled to alpha 2 receptors, we measured cAMP production and show that the alpha 2 agonist B-HT 933 had no effect on basal or stimulated (forskolin, parathyroid hormone) cAMP accumulation in DCT cells but inhibited parathyroid hormone-stimulated cAMP accumulation in proximal tubule cells [2].
• 1. Blood pressure responses to single and multiple bolus doses of the alpha 2-adrenoceptor agonist B-HT 933 were analysed in intact anaesthetized rats which were either normotensive or hypotensive as a result of haemorrhage [12].
• The higher dose of B-HT 933 also decreased the fraction of cardiac output flowing to the kidneys but kidney blood flow was maintained as a result of the increased cardiac output [13].
• Arterial pressure and heart rate were decreased significantly by B-HT 933 (12 mm Hg and 80 beats/min. respectively) [14].
• 1. The dose-related effects of the selective alpha 2-adrenoceptor agonists clonidine, UK-14,304 and B-HT 933 on the body temperature of untreated and reserpine-treated mice were investigated [15].

Anatomical context of B-HT 920

• Relationship between alpha adrenoceptor occupancy and response for the alpha-1 adrenoceptor agonist, cirazoline, and the alpha-2 adrenoceptor agonist, B-HT 933, in canine saphenous vein [16].
• B-HT 933, a selective alpha-2 adrenoceptor agonist, also produced a concentration-dependent contraction in canine pulmonary vein, with the maximal contraction elicited by B-HT 933 being approximately 45% of that produced by norepinephrine [17].
• The effects of the selective alpha-2 adrenoceptor agonists B-HT 920 and B-HT 933 on fluid and electrolyte transport in mammalian small intestine were assessed in vitro and in vivo [18].
• The alpha-2 agonists, guanabenz, UK 14,304 and B-HT 933, equivalently stimulated QO2 in distal tubules, but a spectrum of enhanced oxygen consumption was observed in proximal nephrons [19].
• Yohimbine antagonized in a competitive way the twitch inhibitory effect of B-HT 933 on vas deferens and on MP-LM; the pA2 values were 8.62 and 8.5, respectively [20].

Associations of B-HT 920 with other chemical compounds

• Under conditions of normal pulmonary vascular tone (10 +/- 1 mm Hg), methoxamine, a selective alpha-1 adrenoceptor agonist, and B-HT 933, a selective alpha-2 adrenoceptor agonist, elicited maximal increases in lobar perfusion pressure of 5 and 2 mm Hg above resting pulmonary tone, respectively [21].
• The sympatho-inhibitory effect of alpha 2-agonists (clonidine, guanfacine, B-HT 933) was assessed by recording heart rate in normotensive bilaterally-vagotomized rats [22].
• 2. Both the alpha 1-selective agonist phenylephrine in the presence of 0.3 microM yohimbine and the alpha 2-selective agonist B-HT 933 in the presence of 0.3 microM prazosin elicited prominent and concentration-dependent contractions [23].
• Rilmenidine (1 mg/kg s.c.) and B-HT 933 (2 mg/kg s.c.) induced significant and similar reductions in mean arterial pressure (-24 +/- 2 and -18 +/- 5 mm Hg. respectively) and in heart rate (-62 +/- 29 and -69 +/- 14 beats/min. respectively), whereas the vehicle had no significant hemodynamic effects [24].
• Pretreatment with the alpha-adrenoceptor-blocking drug, piperoxan (100 micrograms/kg), completely abolished the hypotensive response to B-HT 933 (30 micrograms/kg) injected subsequently via the left vertebral artery [25].

Gene context of B-HT 920

• The data indicate that, in the presence of fixed levels of arginine vasopressin, chronic renal denervation prevented the natriuretic and diuretic effect of B-HT 933 in anesthetized rats [14].
• A further dose of B-HT 933 (1 mg kg-1 bolus followed by 100 micrograms min-1 infusion) increased blood pressure by increasing total peripheral resistance, which was accompanied by decreased proportions of cardiac output passing to the heart, liver and testes [12].

Analytical, diagnostic and therapeutic context of B-HT 920

• The selective alpha-2 adrenoceptor agonist, B-HT 933, also increased perfusion pressure in both beds, although the maximum response to B-HT 933 in the saphenous bed was approximately twice that observed in the femoral bed [26].
• 2. Cardiac output, its distribution and tissue blood flows were determined with tracer microspheres in intact anaesthetized normotensive and haemorrhagic, hypotensive rats during depressor (normotensive) and pressor (normotensive and hypotensive) responses to B-HT 933 [12].
• Oral administration of B-HT 933 dose-dependently inhibits dmPGE2-induced enteropooling in conscious rats [18].
• In micropuncture studies, B-HT 933 was without effect on single-nephron glomerular filtration rate or on Na+, K+, and water transport along the superficial proximal tubule, loop of Henle, or distal tubule [27].

References