Hemodynamic Changes that Accompany the Pressor Response to Propranolol in Urethane Anesthetized Rats Subjected to α-Blockade
Bibliographic record
Abstract
It has been shown that a paradoxical pressor response to a beta-blocker occurs in rats given an alpha-blocker. The dual-isotope microsphere technique was used to investigate the hemodynamic changes that accompany the pressor response to propranolol in phentolamine-treated, urethane-anesthetized rats. Rats were divided into four groups (n = 8 per group): group I received 10 min of saline infusion; group II received intravenous infusion of phentolamine (300 micrograms/kg/min) for 10 min; group III received intravenous injection of propranolol (100 micrograms/kg) after 20 min of phentolamine infusion, and group IV received intravenous injection of saline after 20 min of phentolamine infusion. In groups I and IV, saline did not cause any significant hemodynamic changes. In group II, phentolamine decreased the mean arterial pressure (MAP) and total peripheral resistance (TPR) by 34 +/- 3 mm Hg and 0.28 +/- 0.07 mm Hg/min/ml, respectively. Arterial conductances in the skeletal muscle and skin were increased to 157 and 165% of control values, respectively. Cardiac output and conductances in other tissues and organs were not significantly affected. In rats given phentolamine (group III), propranolol raised MAP (+40 +/- 2 mm Hg) by increasing TPR (+0.41 +/- 0.03 mm Hg/min/ml). Vascular conductances in the skeletal muscle, skin and kidneys were decreased to 38, 57 and 69% of control values, respectively. Conductances in other tissues and organs were not significantly affected. Our results show that propranolol raised MAP by increasing flow resistance, primarily via the reversal of the vasodilator effects of phentolamine in the muscle and skin.
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How this classification was reachedexpand
Full frame distilled prediction
Teacher imitationNot calibrated prevalence, not ground truth. Human validation pending. Learned from the 10,348 direct Codex labels and 10,348 direct Gemma labels. Candidate is the union of thresholded teacher heads; consensus is their intersection. These outputs are machine_predicted_unvalidated and are not human labels or direct frontier model labels.
Codex and Gemma teacher scores by category
| Category | Codex | Gemma |
|---|---|---|
| Metaresearch | 0.001 | 0.000 |
| Meta-epidemiology (narrow) | 0.000 | 0.000 |
| Meta-epidemiology (broad) | 0.001 | 0.000 |
| Bibliometrics | 0.000 | 0.000 |
| Science and technology studies | 0.000 | 0.000 |
| Scholarly communication | 0.000 | 0.000 |
| Open science | 0.000 | 0.000 |
| Research integrity | 0.000 | 0.000 |
| Insufficient payload (model declined to judge) | 0.000 | 0.000 |
Machine scores (provisional)
The two teacher heads of the student model, read on this work. A score orders the frame for review; it never asserts a category, and the validation status ships verbatim with every row.
Baseline scores from an immature model (maturity gate not passed, 7 training rounds). Scores rank; they never assert a category.
score_only:v0-immature-baseline · verbatim from the scoring run: score_only means the number may rank works, and no category label ships from itClassification
machine, unvalidatedMachine predicted; a candidate call from one teacher head, not a consensus.
How this classification was reached, model by model and score by score, is at the end of the page under "How this classification was reached".