Abstract
The severity of ventricular arrhythmias induced by coronary artery occlusion and reperfusion has been examined in control rats and animals made hypothyroid by pretreatment with 6-propylthiouracil (PTU). The maximal driving frequency and sensitivity of isolated left atria and papillary muscles to isoprenaline and to phenylephrine in the presence of propranolol, were also examined in tissues from control and hypothyroid animals. Pretreatment with PTU resulted in a potentiation of responses to the α-adrenoceptor agonist phenylephrine in both left atria and papillary muscles, while responses to isoprenaline were depressed in left atria but unaltered in papillary muscles from hypothyroid animals. In rats subject to coronary artery occlusion, PTU pretreatment reduced the incidence of ventricular fibrillation during acute myocardial ischaemia and abolished reperfusion-induced ventricular fibrillation. Mortality during myocardial ischaemia and reperfusion was also abolished. Diastolic blood pressure was similar in hypothyroid and control animals, but there was a small reduction in systolic blood pressure and a marked decrease in heart rate in PTU pretreated animals. These results demonstrate that PTU-induced hypothyroidism represents a condition where cardiac α-adrenoceptor-mediated responses are enhanced but the severity of ischaemia- and reperfusion-induced arrhythmias is reduced.
| Original language | English |
|---|---|
| Pages (from-to) | 95-100 |
| Number of pages | 6 |
| Journal | British Journal of Pharmacology |
| Volume | 98 |
| Issue number | 1 |
| DOIs | |
| Publication status | Published - 1 Jan 1989 |
| Externally published | Yes |
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Ventricular fibrillation is reduced in hypothyroid rats with enhanced myocardial α-adrenoceptor responsiveness. / Chess-Williams, R.; Coker, S. J.
In: British Journal of Pharmacology, Vol. 98, No. 1, 01.01.1989, p. 95-100.Research output: Contribution to journal › Article › Research › peer-review
TY - JOUR
T1 - Ventricular fibrillation is reduced in hypothyroid rats with enhanced myocardial α-adrenoceptor responsiveness
AU - Chess-Williams, R.
AU - Coker, S. J.
PY - 1989/1/1
Y1 - 1989/1/1
N2 - The severity of ventricular arrhythmias induced by coronary artery occlusion and reperfusion has been examined in control rats and animals made hypothyroid by pretreatment with 6-propylthiouracil (PTU). The maximal driving frequency and sensitivity of isolated left atria and papillary muscles to isoprenaline and to phenylephrine in the presence of propranolol, were also examined in tissues from control and hypothyroid animals. Pretreatment with PTU resulted in a potentiation of responses to the α-adrenoceptor agonist phenylephrine in both left atria and papillary muscles, while responses to isoprenaline were depressed in left atria but unaltered in papillary muscles from hypothyroid animals. In rats subject to coronary artery occlusion, PTU pretreatment reduced the incidence of ventricular fibrillation during acute myocardial ischaemia and abolished reperfusion-induced ventricular fibrillation. Mortality during myocardial ischaemia and reperfusion was also abolished. Diastolic blood pressure was similar in hypothyroid and control animals, but there was a small reduction in systolic blood pressure and a marked decrease in heart rate in PTU pretreated animals. These results demonstrate that PTU-induced hypothyroidism represents a condition where cardiac α-adrenoceptor-mediated responses are enhanced but the severity of ischaemia- and reperfusion-induced arrhythmias is reduced.
AB - The severity of ventricular arrhythmias induced by coronary artery occlusion and reperfusion has been examined in control rats and animals made hypothyroid by pretreatment with 6-propylthiouracil (PTU). The maximal driving frequency and sensitivity of isolated left atria and papillary muscles to isoprenaline and to phenylephrine in the presence of propranolol, were also examined in tissues from control and hypothyroid animals. Pretreatment with PTU resulted in a potentiation of responses to the α-adrenoceptor agonist phenylephrine in both left atria and papillary muscles, while responses to isoprenaline were depressed in left atria but unaltered in papillary muscles from hypothyroid animals. In rats subject to coronary artery occlusion, PTU pretreatment reduced the incidence of ventricular fibrillation during acute myocardial ischaemia and abolished reperfusion-induced ventricular fibrillation. Mortality during myocardial ischaemia and reperfusion was also abolished. Diastolic blood pressure was similar in hypothyroid and control animals, but there was a small reduction in systolic blood pressure and a marked decrease in heart rate in PTU pretreated animals. These results demonstrate that PTU-induced hypothyroidism represents a condition where cardiac α-adrenoceptor-mediated responses are enhanced but the severity of ischaemia- and reperfusion-induced arrhythmias is reduced.
UR - http://www.scopus.com/inward/record.url?scp=0024401471&partnerID=8YFLogxK
U2 - 10.1111/j.1476-5381.1989.tb16867.x
DO - 10.1111/j.1476-5381.1989.tb16867.x
M3 - Article
VL - 98
SP - 95
EP - 100
JO - British journal of pharmacology and chemotherapy
JF - British journal of pharmacology and chemotherapy
SN - 0007-1188
IS - 1
ER -