Z. Merican

The effects of propranolol on skeletal muscle contraction, lipid peroxidation products and antioxidant activity in experimental hyperthyroidism

1. The mean levels of lipid peroxidation products, namely conjugated diene and malonaldehyde, were increased in the soleus muscles of hyperthyroid cats, while the mean glutathione peroxidase activity was decreased. No corresponding similar changes were noted in the fast extensor digitorum longus muscles and serum. 2. Propranolol administration prevented the increase in conjugated diene level in the soleus muscles of hyperthyroid cat but not the malonaldehyde level. It also prevented the reduction in glutathione peroxidase activity in the slow oxidative soleus muscles of hyperthyroid cats. 3. Maximal twitch tension, subtetanic tension and maximum tetanic tension of soleus and EDL muscles were reduced in hyperthyroid cats. Propranolol administration for 5 weeks to hyperthyroid cats did not prevent the reduction in tension of contractions of these muscles. 4. It is suggested that lipid peroxidation might not be responsible for the myopathy in hyperthyroidism and propranolol administration does not improve skeletal muscle function in hyperthyroid animals.

THE EFFECTS OF NALOXONE, DEXAMETHASONE, DEOXYCORTICOSTERONE AND 17‐HYDROXYPROGESTERONE ON BLOOD PRESSURE RESPONSES OF NORMAL AND ADRENALECTOMIZED RATS DURING HYPOVOLAEMIC SHOCK

SUMMARY

Effects of thyroxine treatment on contractions of soleus muscles of anaesthetized cats.

1. The effects of chronic thyroxine treatment on cat soleus muscle contractions were studied.

THE EFFECT OF CORTICOSTEROID PRETREATMENT IN VIVO ON THE CONTRACTION OF GUINEA‐PIG ILEUM AND DUODENUM

1. The effects of corticosteroid pretreatment on the contraction caused by acetylcholine or electrical stimulation of guinea‐pig ileum and duodenum were studied.

THE EFFECTS OF THYROXINE TREATMENT ON SLOW‐ AND FAST‐CONTRACTING SKELETAL MUSCLE CONTRACTIONS OF THE CAT AND THEIR CYCLIC AMP LEVEL

1. The effects of thyroxine treatment on soleus and extensor digitorum longus (EDL) muscle contractions and their cyclic adenosine 3′,5′‐monophosphate (cyclic AMP) levels were examined in anaesthetized cats.

FURTHER EVIDENCE OF THE ROLE OF CYCLIC AMP AS A MEDIATOR OF THE DEPRESSANT EFFECTS OF β‐ADRENOCEPTOR AGONISTS AND PHOSPHODIESTERASE INHIBITORS ON SLOW‐CONTRACTING MAMMALIAN SKELETAL MUSCLES

1. The depressant effects of β‐adrenoceptor agonists and phosphodiesterase inhibitors on contractions of slow‐contracting mammalian skeletal muscles are associated with increased muscular cyclic AMP levels.

EFFECTS OF α- AND β-ADRENOCEPTOR AGONISTS AND A PHOSPHODIESTERASE INHIBITOR (ICI 63 197) ON CYCLIC AMP AND GMP LEVELS IN BOVINE SPLENIC NERVE

1. Cyclic AMP and cyclic GMP levels were determined in bovine splenic nerve segments in the absence and presence of (±) ‐ isoprenaline, (‐)‐phenylephrine, clonidine and ICI 63 197 (a phosphodiesterase inhibitor). The chosen concentrations of adrenoceptor agonists were those which are known to affect stimulation‐induced overflow of noradrenaline from nerve terminals.

The effects of 4-methyl-2-thiouracil on fibre type and cross-sectional area in the soleus muscle of the rat.

1. The effects of 4‐methyl‐2‐thiouracil (MTU, 0.1% in drinking water) on the composition and cross‐sectional area of muscle fibres of the rat soleus muscle were studied.

THE EFFECTS OF SIMULTANEOUS ATROPINE AND LABETALOL ADMINISTRATION ON CARDIOVASCULAR PARAMETERS DURING ANTICHOLINESTERASE POISONING IN ANAESTHETIZED CAT

1. The effects of atropine administration during anticholinesterase poisoning on heart rate, blood pressure and electrocardiographic changes (ECG) were studied in the cat.