Ans. b. They increase bronchial responsiveness to salbutamol Coicosteroids has a dual effect in acute asthma with an early facilitator effect on airway beta-2 adrenoreceptor sensitivity and a later effect on airway inflammation, which fuher emphasizes the need fir coicosteroids to he administered as early as possible during an acute asthma attack."he molecular mechanism of action of coicosteroids involves several effects on the inflammatory process. The major effect of coicosteroids is to switch off the transcription of multiple activated genes that encode inflammatory proteins such as cytokines, chemokines, adhesion molecules, and inflammatory enzymes. This effect involves several mechanisms, including inhibition of the transcription factor NF-KB, but an impoant mechanism is recruitment of HDAC2 to the inflammatory gene complex, which reverses the histone acetylation associated with increased gene transcription. Coicosteroids also activate anti-inflammatory genes, such as mitogen-activated protein (MAP) kinase phosphatase-1, and increase the expression of IQ-receptors. Most of the metabolic and endocrine side effects of coicosteroids are also mediated through transcriptional activation.