Endogenous α-calcitonin-gene-related peptide promotes exercise-induced, physiological heart hypertrophy in mice

AIM

It is unknown how the heart distinguishes various overloads, such as exercise or hypertension, causing either physiological or pathological hypertrophy. We hypothesize that alpha-calcitonin-gene-related peptide (αCGRP), known to be released from contracting skeletal muscles, is key at this remodelling.

METHODS

The hypertrophic effect of αCGRP was measured in vitro (cultured cardiac myocytes) and in vivo (magnetic resonance imaging) in mice. Exercise performance was assessed by determination of maximum oxygen consumption and time to exhaustion. Cardiac phenotype was defined by transcriptional analysis, cardiac histology and morphometry. Finally, we measured spontaneous activity, body fat content, blood volume, haemoglobin mass and skeletal muscle capillarization and fibre composition.

RESULTS

While αCGRP exposure yielded larger cultured cardiac myocytes, exercise-induced heart hypertrophy was completely abrogated by treatment with the peptide antagonist CGRP(8-37). Exercise performance was attenuated in αCGRP(-/-) mice or CGRP(8-37) treated wild-type mice but improved in animals with higher density of cardiac CGRP receptors (CLR-tg). Spontaneous activity, body fat content, blood volume, haemoglobin mass, muscle capillarization and fibre composition were unaffected, whereas heart index and ventricular myocyte volume were reduced in αCGRP(-/-) mice and elevated in CLR-tg. Transcriptional changes seen in αCGRP(-/-) (but not CLR-tg) hearts resembled maladaptive cardiac phenotype.

CONCLUSIONS

Alpha-calcitonin-gene-related peptide released by skeletal muscles during exercise is a hitherto unrecognized effector directing the strained heart into physiological instead of pathological adaptation. Thus, αCGRP agonists might be beneficial in heart failure patients.

[Febrile convulsions: assessment of current status]

Febrile seizures are the most frequent neurologic disorders during childhood. The pathogenesis is not clear even today. Viral infections of the upper airways, exanthema subitum, acute otitis media, infection of the urinary tract and febrile reactions after vaccination are the most frequent precipitating factors. Predictors in identifying children with very high risk of recurrence are young age at onset, family history of febrile seizures in a first-degree relative, a history of recurrent febrile seizures and a lower degree of fever at the onset of febrile seizures. A family history of epilepsy, neurodevelopmental abnormalities and a lower degree of fever at the onset of febrile convulsion are predictors of later epilepsy in children who have febrile seizures. The prognosis of febrile seizures is very good. In the acute situation, rectal diazepam should be given in the event of prolonged febrile seizures (> 3 minutes) only. Intermittent diazepam therapy and long-term antiepileptics are not recommended. The best prophylactic treatment is education and reassurance for parents and children.

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Experience is reported of palliative treatment for malignant obstructive jaundice by plastic drain positioned in the biliary tract during endoscopic retrograde cholangiopancreatography (ERCP). In the period January 1989 to December 1991, 35 plastic drains (10-12 French) were implanted in 22 patients of mean age 70 (range 51-88) years because of obstruction due to biliary tract carcinoma (n = 10), metastases (n = 5), pancreatic carcinoma (n = 4) and papillary carcinoma (n = 3). Endoscopic positioning was successful in 86% of cases. The early complication rate was 4.5% (cholangitis) and the 30-day mortality 14%. In 89% of cases drainage was effective and the obstructive jaundice subsided within 3 months. Late complications occurred in 36% of patients, involving cholangitis due to drain obstruction (n = 5) and drain displacement (n = 2). In 27% of patients the drain had to be changed 1-3 times, on the first occasion after an average of 146 (range 14-421) days. The patients' median survival was 5 months.

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Report on a case of severe megaloblastic anemia in a vegetarian, associated with marked erythroleukemic blood findings probably caused by infections (bronchopneumonia, asthmatic bronchitis, urinary tract infection) and severe heart failure. Successful treatment of the above mentioned complications resulted in almost complete disappearance of pathologic cells from the blood even before vitamin B12 treatment was started. With this therapy complete recovery was achieved and the signs suspect for erythroleukemia in blood and bone marrow disappeared definitively. The case also fulfilled all the criteria of pernicious anemia (Schilling's test and determination of intrinsic factor were not done).