( ( In ( ( the ( workers ' ) ) case ) ) ( , ( ( the nitroglycerin ) ( ( ( ( ( ( was ( ( ( ( dilating ( blood vessels ) ) ( in ( the brain ) ) ) , ) ( causing ( migraine headaches ) ) ) ) , ) but ) also ) ( was ( ( ( ( dilating ( blood vessels ) ) ( in ( the ( cardiovascular system ) ) ) ) , ) ( decreasing ( ( the ( heart 's ) ) workload ) ) ) ) ) . ) ) ) )
(ROOT (S (PP (IN In) (NP (NP (DT the) (NNS workers) (POS ')) (NN case))) (, ,) (NP (DT the) (NN nitroglycerin)) (VP (VP (VBD was) (VP (VBG dilating) (NP (NN blood) (NNS vessels)) (PP (IN in) (NP (DT the) (NN brain))) (, ,) (S (VP (VBG causing) (NP (JJ migraine) (NNS headaches)))))) (, ,) (CC but) (ADVP (RB also)) (VP (VBD was) (VP (VBG dilating) (NP (NN blood) (NNS vessels)) (PP (IN in) (NP (DT the) (JJ cardiovascular) (NN system))) (, ,) (S (VP (VBG decreasing) (NP (NP (DT the) (NN heart) (POS 's)) (NN workload))))))) (. .)))
In the workers' case, the nitroglycerin was dilating blood vessels in the brain, causing migraine headaches, but also was dilating blood vessels in the cardiovascular system, decreasing the heart's workload.
(ROOT (S (SBAR (WHADVP (WRB When)) (S (NP (NP (NN blood) (NNS vessels)) (PP (IN in) (NP (DT the) (NN head)))) (VP (VBP dilate)))) (, ,) (NP (NP (DT a) (NN migraine)) (, ,) (NP (DT a) (JJ severe) (NN headache)) (, ,)) (VP (MD can) (VP (VB occur))) (. .)))