The effect of forskolin on the isometric contraction of the isolated hemidiaphragm of the rat

• Published in: British journal of pharmacology Vol. 88; no. 4; pp. 791 - 797
• Main Authors: Prostran, Milica, Varagić, V.M.
• Format: Journal Article
• Language: English
• Published: Oxford, UK Blackwell Publishing Ltd 01-08-1986; Nature Publishing
• Subjects: Aminophylline - pharmacology; Animals; Biological and medical sciences; Calcium - metabolism; Colforsin - pharmacology; Dose-Response Relationship, Drug; Drug Synergism; Electric Stimulation; Female; Isometric Contraction - drug effects; Isoproterenol - pharmacology; Male; Medical sciences; Muscle; Muscle Contraction - drug effects; Pharmacology. Drug treatments; Rats; Calcium; Rat; Electrical stimulus; Rodentia; Contractility; In vitro; Contraction; Isolated organ; Dose activity relation; Vertebrata; Mammalia; Animal; Forskolin; AMP-3',5'; Muscle; Diaphragm
• ISSN: 0007-1188; 1476-5381
• DOI: 10.1111/j.1476-5381.1986.tb16251.x

1
The effects of forskolin on the parameters of the isometric contraction alone and in combination with aminophylline and isoprenaline were studied on the isolated hemidiaphragm of the rat during direct electrical stimulation.
2
Forskolin (2.6−18.2 μmol l−1) produced a concentration‐dependent increase in tension developed (Td) and, to a lesser extent, in the maximum rate of rise in tension (dT/dt max).
3
The dose‐response curve for the action of forskolin (2.6−18.2 μmol l−1) on Td was shifted to the left in the presence of a standard concentration of aminophylline (0.32 mmol l−1).
4
Forskolin (5.2 μmol l−1) produced a further and significant increase in both Td and dT/dt max in the presence of isoprenaline (0.24 μmol l−1) in the bath.
5
In a calcium‐free medium, the effects of forskolin (7.80 and 18.2 μmol l−1) on Td and dT/dt max were significantly weaker than in a medium containing calcium.
6
These data indicate that forskolin increases the isometric contraction of the isolated hemidiaphragm probably by activating the adenosine 3′:5′‐cyclic monophosphate (cyclic AMP) generating system. These effects are possible only in the presence of calcium.