Search PubMed⌕ Search

Biomedical subjects

H H Siddiqui

Publications and source records attributed to H H Siddiqui.

At least 19 recordsLinked to original sources
PubMed1993

Cephalosporins.

Explore the source record for details and available documents.

Bacterial Infections↗
PubMed1990

Increased brainstem angiotensin-I levels in chronic 2 KIC hypertensive rats.

A study was undertaken on the role of brainstem renin-angiotensin system in maintenance of hypertension in chronic renovascular hypertensive rats. Hypertension was induced by unilateral renal artery clamping, while the contralateral kidney was left intact (2 KIC). Blood pressure (BP), plasma renin activity (PRA) and brainstem angiotensin (ang-I) levels were measured after 24 days, in hypertensive and sham-operated animals. In separate subgroups of these animals, the effect of intracerebroventricular administration of captopril on the parameters listed was studied. The results showed high ang-I levels in 2 KIC rats as compared to controls (P less than 0.05). Captopril administration (500 micrograms/50 microliters icv) caused a fall in BP and increase in brainstem ang-I levels (P less than 0.01). In control animals, however, captopril produced a rise in BP without any significant change in brainstem ang-I levels. Peripheral plasma renin activity was normal, despite significant sodium retention in 2 KIC rats. The results are suggestive of activation of brainstem renin-angiotensin system (RAS) in chronic 2 KIC hypertension.

Angiotensin I↗
PubMed1983

Nature of the beta-adrenoreceptors in the tracheal smooth muscle of the adult pig.

Relaxant responses to isoprenaline (ISO), adrenaline (ADR) and noradrenaline (NA) were investigated on carbachol-contracted, isolated tracheal smooth muscle preparations of the adult pig to determine the nature of the beta-adrenoreceptors present. The order of relaxant potencies of the catecholamines on this preparation was ISO greater than ADR greater than NA. The potency ratio at 37 degrees C was 1:0.06:0.005. This suggests that beta 2-adrenoreceptors predominate in isolated tracheal smooth muscle of the adult pig. Though the order of potency for the above catecholamines did not change, at the lower temperatures of 29 degrees and 33 degrees C, the potency ratios were slightly modified to 1:0.0.98:0.004 and 1:0.07:0.004 respectively. pA2 values on pig tracheal smooth muscle were 8.65 and 9.13 respectively, for the non-selective beta-blockers propranolol and alprenolol, and 5.63, 5.20 and 6.26 respectively, for the beta 1 selective blockers practolol, atenolol and metoprolol and 6.82 for the beta 2 selective beta-blocker, H 35/25. The results suggest the existence and predominance of beta 2-adrenoreceptors in tracheal smooth muscle of the adult pig.

Adrenergic beta-Agonists↗
PubMed1983

Effect of beta-adrenergic blockers on isolated coronary arterial strip and tracheal smooth muscle of pig.

Isolated coronary arterial strip and tracheal smooth muscle of pig, containing predominantly beta 1- and beta 2-adrenoceptors respectively, have been used for estimating the comparative potency of nine beta-adrenergic blocking agents. The order of potency of the antagonists on the isolated coronary arterial strip was propranolol greater than alprenolol greater than H 64/52 greater than H 64/55 greater than practolol greater than H 87/07 greater than atenolol greater than metoprolol greater than H 35/25, whilst the order of potency on the pig tracheal smooth muscle was alprenolol greater than propranolol greater than H 35/25 greater than H 87/07 greater than H 64/55 greater than H 64/52 greater than metoprolol greater than practolol greater than atenolol. Propranolol and alprenolol were almost equipotent in both the preparations and hence were nonspecific. Although practolol, metoprolol, H 64/55 and H 87/07 were beta 1-selective, their selectivity ratio was comparatively smaller than that of atenolol and H 64/52. The study indicates that H 64/52 and atenolol are the most specific beta-adrenergic blocking agents on isolated coronary arterial strip of pig and that their beta 1/beta 2-ratios are 126 and 120 respectively. H 64/52 like atenolol may be of therapeutic value in cardiovascular disorders.

Adrenergic beta-Antagonists↗
PubMed1977

Feline endotoxin shock: effects of methylprednisolone on kininogen-depletion, on the pulmonary circulation and on survival.

1 Escherichia coli endotoxin, administered intravenously in a dose of 2 mg/kg to pentobarbitone anaesthetized, artificially ventilated cats resulted in pulmonary hypertension, systemic hypotension and an immediate (1-2 min) 30-40% reduction in plasma kininogen, an effect which probably indicates a release of plasma kinins. 2 Methylprednisolone (30 mg/kg), when administered 30 min before endotoxin, did not influence the endotoxin-induced pulmonary hypertension or systemic hypotension but completely prevented the depletion of plasma kininogen. 3 In spontaneously breathing cats, methylprednisolone, administered 30 min after endotoxin, caused a rapid repletion of kininogen and prolonged survival (47% at 6 h compared to 10% in the endotoxinalone animals). Methylprednisolone did not appear to influence lactate production or the hyperventilation observed during the delayed endotoxin shock phase. 4 It is concluded t,at methylprednisolone does not prevent the release, by endotoxin, of a pulmonary vasoconstrictor prostaglandin, or its effects, but that perhaps by preventing kinin release it may reduce endotoxin-induced capillary leakage.

Animals↗